On a recent jog through my local park in London, something stopped me in my tracks. As I came around a corner in a wooded area, I passed a young woman standing in the middle of the path, looking around frantically, sobbing. While I usually tend to leave people who are crying in public to themselves, this scene sent off alarm bells in my head. This woman needs help, I thought. I had to stop.

"Hey, are you okay?" I asked. When I got close enough to look at her, I realized she couldn't have been much older than 18 or 19. She squinted at me, and let out one of those loud, gut-spewing, choking sobs.

"No," she said. "Please help me. He's taken my glasses."

What? Who?

Between gasps, she explained that she and her boyfriend had just been in a fight, and it had ended with him storming off, taking her glasses with him. She had poor eyesight, and couldn't see well enough to find her way out of the park. To make matters worse, she wasn't from London, and her phone was dead.

She was stranded, far from home, and unable to see. No wonder she was so upset. What kind of jerk does that? I thought.

The sun was setting. My first idea was to get her out of the park and into a well-lit public space where we could figure out the next steps. So we walked. I tried to calm her by asking where she was from, how long she was in town. But she was distracted. She kept looking around, wide-eyed and terrified, searching for her boyfriend. Then she spotted him. He was lurking in the shadows, waiting. He was a tall, thin man, probably about the same age as her. I could tell by the way she became immediately panicked that she was afraid of him.

"He'll probably yell at you," she warned me as we neared him. "He has a bad temper. He'll probably be mad at me because I asked for help."

Without thinking, I walked up to him and asked if he knew where the glasses were. "I threw them in the river," he said. This made the woman burst into tears again, and she asked me to call the police. I whipped out my phone and began to dial, but before I could press the call button, the man pulled the glasses out of his pocket and slammed them into her open palm with force. "They're right here," he said with a grumble. "I was just kidding."

Then he turned to me and became verbally aggressive. "Who the f— do you think you are? You think I'm abusive or something? This is none of your business."

I tried to ignore him and offer my help to the woman. I said I was worried about her. Would she like to come back to my place? Did she have someone she could call? The man eventually wandered off down the path and left us alone. That's when she told me she was pregnant with his child, and their relationship was fraught with physical and verbal abuse. "He would never really hurt me," she said. "Sure, we fight a lot, and sometimes we hit one another, but all relationships have their ups and downs, right? He would never actually do anything to hurt me."

I wanted to tell her to snap out of it, that non-consensual physical violence is not normal in a relationship, and that this would only escalate. She had to get out now. But I thought it would be futile. As is the case with many abuse victims, she said she needed to be with him. She was in love. She begged to go after him. I knew I wasn't going to be able to convince this young woman to change her life here and now on the sidewalk, so I let her go. But not before giving her my number. "Call me anytime," I said.

As I tried to go about my business that evening, I couldn't shake the feeling that I'd messed up. Did I do everything I could? Should I have called the police? Forced her to come home with me?

This isn't something they teach you about in school. There's no real protocol. People tend to not get involved, even when they should.

In a recent Swedish social experiment, researchers exposed people to what looked like an instance of domestic abuse. Fifty-three people saw the staged abuse. Just one of them actually intervened.

Part of the reason for our inaction in the face of public abuse may stem from the fact that most abuse happens behind closed doors. "With most abusers, they're smarter than that," says Bea Arthur, a licensed therapist and women's advocate who worked as a domestic violence counselor for two years. "They're very charming, and the woman defends him and doesn't say anything. So people don't know what's going on."

That's true. But it needs to change. We need to educate people on how to deal with abuse when it does happen publicly, or we risk them ignoring the situation and leaving the victim to suffer.

So, if you do find yourself in this unfortunate situation, here are some guidelines.

1. Call the police.

Many domestic violence groups say this is the best thing you can do. "If you see an incident of domestic violence, always call the police rather than intervening, as it could put you directly at risk," Polly Neate, chief executive of Women's Aid, told HuffPost. "It could also make the abuse worse, or if the victim is frightened of her abuser she may also turn against you out of fear."

In other words, I might have messed up by getting involved myself. But it also stands that sometimes calling the police "can make things harder on the women," says Arthur. This is especially true if the victim is an undocumented immigrant and risks deportation, or is financially or physically reliant on their abuser. And while you might think that calling the police will put a stop to the abuse, that's unlikely. Victims often go back to their abusers. "Everyone blames women for staying with the guy, but a lot of times it's a pattern of power and control," says Arthur. "They find people who are susceptible. They're predators." The victim will probably go back, and when they do, their abuser is going to be angry. The violence is likely to escalate.

But interfering yourself could put you in physical danger. I only thought about this after the fact, when I was at home making dinner and still turning the whole thing over and over in my head. I realized things could have gone much worse. What I did wasn't necessarily wrong — but it also wasn't safe.

2. Make sure you're in a public space.

If possible, move to a well-lit area with some foot traffic. If things do escalate further, you need as many witnesses as possible, says Arthur.

3. Speak only to the victim.

"The best thing to do is to speak directly to the woman, because it reminds her that she has options, that she's a person," says Arthur. "For her, this is embarrassing. They have a lot of shame about the situation, they keep it a secret. She believes it's her fault. So, speak supportively, warmly."

Directing your words toward the victim does two other things: First, it starves the abuser of attention. In some cases, as in my experience, they will simply walk away if they don't get the feedback they desire. Second, it demonstrates coping behavior that the victim could mirror. "Show her what it looks like to ignore him," Arthur says.

4. Make sure the victim has someone to help her.

"Ask if there's anybody she wants you to call," Arthur recommends. "These guys sometimes take their cell phones." In my case, the victim's phone was dead. So I sent her a text message that she'd receive whenever she could find a charge, to make sure she had my number. "Giving them a lifeline to the outside world and outside of the abuse is the best thing you can do," Arthur says.

Later in the evening, when I was getting ready for bed, I got a text message: "Hi Jess, thank you so much for this evening. I really appreciate it. I'm on my way home now. Thank you again."

I ended the correspondence by giving her the number of a domestic violence hotline. I'll never know if she used it, but I really hope she did.

If you are the victim of domestic violence, you can call the National Domestic Violence Hotline if you're in the U.S.; call the Refuge helpline if you're in the U.K.