Noob here, need help

Hello,

I don't even know how to approach this. I need some advices from experienced people on my situation.
So i've meet this girl 3 years ago. For about 1 year, we were just friends. Then we started to hang out more and more and then i finally told her what i feel. We've been in a relationship for almost 6 months, then i said i can't continue anymore and we broke up, reason : communication. 4 months and she's back.. 2-3 weeks of ''relationship'' and yeah.. again.. 2 months and 2 weeks i think and shs's back again.. exactly like the last attempt, less than 1 month of relationship and we break up.. every time the problem was communication: who sends messages first , who calls, who asks to go out.. Right , so after our last breakup,2-3 weeks after i was home alone and i felt lonely , so i contacted her, she was willing to try again... nope didn't work. 2 months and 2 weeks i belive after our last breakup, here she comes again. This time motivated more than ever saying that she loves me, saying words she never said to me before, saying that she wants no more breakups, that it's enough. But here's the thing.. talking with her about everything, she said that in those 4 months, for about 1 month she was sleeping with another guy. Now i understand that we weren't together anymore and she and i were free to do anything, but huts like hell. She told me that she can't say i love u and lying at the same time, because i asked her directly about sleeping with someone else. The last breakup was due to me beliving she's cheating on me, that ''proved '' to be wrong, i mean i know she didn't do that, i don't even think about it anymore . Now.. i feel this ''fire'' inside me because she slept with that guy + i got this irrational fear of cheating because my mom cheated on my dad just recentlly, now i know all this will go away in time, like maybe half a year or something, it's not that i don't belive in myself, i'm not confident, i'm in fact, it's just that i don't trust her. So the score is 3 to 1 .. actually 3 to 0. If i wasn't home alone i would've never contacted her. Every single time it was me who said we need to breakup, she literally never said that she wants to breakup with me.

I would like some advices from someone who can see the whole situation clearly, i sadly don't. I'm open to everything. Some of my friends told me a long time ago to let her go... forever, i didn't and i kind of regret that. When i heard a couple of days ago about her sleeping with another guy in those 4 months, i wanted to leave her, but she came after me and was shaking, huging me and explaining herself.. so yeah.. still together. She doesn't come back for my money or anything, money is out of the question.

First time posting, Thank you for reading!