I (19f) recently got diagnosed with BPD. It has made me frightened but it was also kind of relieving to know what I have and how to treat it.

I also recently broke up with my 3 year old relationship (19m) even though we still love each other, because of big lack of communication and his lack of motivation which made our relationship boring and exhausting. However, the biggest problem was my extreme anger outbursts. I would suddenly get very angry, and if he didn't distance himself from me, I would hit him. I felt terrible for it, but I couldn't find a way to restrict it, so i figured out it was better to free him from this situation, even though he didn't want to leave me.

In the meanwhile, I reconnected with an old friend (19m) who confessed he had feelings for me after a while. (He is very communicative, affirmative, romantic and spontaneous, perfect fit for me.) I told him that I have many psychological problems and I'm not capable of being in a relationship yet and we ended up staying friends. However, I let my feelings for him conquer me and I kissed him. 

This incident started a vicious circle of me distancing myself from him (because I was thinking of getting back together with my ex) and then kissing him again. At this point we're together, but one day I feel like I want him, the other like I want my ex. My feelings are a true rollercoaster and I feel like I can't handle them. The worst part is that I have extreme anger outbursts for him too, I often have a huge desire to hit him.

Apart from the fact that I don't know who of these two people to choose, I don't know how to handle the bpd symptoms that I talked about. What do I do?