Need some advice please

So i’ve been with my boyfriend for almost 2 years now, we were living together last year but this year i had to move to another city because of my studies, at the beginning of our relationship everything was okay until i started to notice that he talked a lot with random girls that he didn’t know and it was clearly not a friendship that he was looking for with this girls. He was trying all time to convince me that it was just a friendship and nothing more until july when i red some of his conversations and it was sooo much more than friendship (one of the girls was his ex) but he never met any of them, i confronted him we talked about it i broke up with him but he never left me go he was trying to arrange things and prove that he loves me... after that we got back together met his parents and he met my parents as well ... after that i moved to another city i went to see him a weekend every 2 weeks... until last month i went to celebrate my birthday with him, in the morning of the day after my birthday i see some weird txt messages from some girl i asked him who was she he lied saying she’s a friend turns out at the end with the help of one of my friends that he was dating her for tow months and clearly he wasn’t planning to break up with her... he was tow timing... so i was upset tried to break up with him he’ve done all that he could so that i don’t leave him... it was so hard for me he always blamed me for this saying that i am the one who moved out and that we didn’t see each other enough time and that as a man he had sexual needs and that’s why he was seeing another girl... and that he knows he have been a bad person to me and that it was all because in a lot of his previous relationship his ex’s broke his heart and that he became just like them... playing with people’s feelings....

I tried to forgive him but i just can’t get over the fact that he was cheating on me and that he dated her for two months and probably if i didn’t discover this whole thing up he would’ve been dating her until now... i just don’t know how to trust him anymore... and i just don’t know what to do...

what do you think about this whole situation ?