Hi Sonia, what I see here is that you have a conflict between what your heart truly wants and what you fear dictates you from your emotional baggage. People normally attract "abusive" relationships to them when they are disempowered in multiple spheres of their life. You attract a violent partner so you can one day step up to your true strength, and say : "Enough is enough!" , becoming the independent woman that you deserve to be.
I've worked with abused women in the past and they told me that the boyfriend was reflecting the inner "beating up" they said to themselves every day.
You have no need to be ashamed of your hidden passion to cut men's hair. Realize that saying that all men are abuser is a very strong label. I understand you suffered in the past, but I am sure you already know that the Truth is not the black and white labels we put on people.
Take the time to be grateful for all the other masculine figures you have right now in your life or had in the past. Think about the beautiful service you can offer to all those men who take care of their families, or elderly men who just want to look great.
In my opinion, focusing on One Thing is wise, but don't you think cutting hair is your one thing? Isn't it very limiting in career fulfillment and financial abundance to only provide value to one gender? I think you would honour your True Self by diving right into it and act even if you doubt.