My Boyfriend Cheated On Me Three Times?

Hi I (17F) have a boyfriend (17M) we been together since High School started. An on three different occasion I found out girls were talking to him the first time was a year into our relationship and they didn't get farther then meting once or twice as far as I know. I broke up with him after I confronted him about it but we got to talking an he let me know she was "delusional". I stopped caring and got back with him. The second time was weird he was talking at a girl for a youtube channel him an his friends was trying to make, despite him dating me all because I was saying how I will go to this party that I didn't end up going to. Now the third time is feel on cheating listening to this bullshit.

His homeboy was trying to talk to this girl, mind you at this point we been together for three years opened up to each other been in deep shit for each other his friends knows how much and how deep my love is for him and its not like I dont show it either I buy gifts and im extremely affectionate right, so since his homeboy wanted a girl he had to help him by talking to that girl's friend thats into him.

This was a dry time for the both of us because he is busy with work and helping out his dad but he's doing all this for his homeboy while I'm here happy to be with him, by the end of the month they're dating but he claims it was just for his homie and he wasn't even into it for real.

All the things you're thinking is 110% the things I told him.

I really love him and i want to stay but its like why? He will say 'idk' and thats his answer I can articulate my thoughts, feelings, and my emotions so he knows what I'm saying say why I'm saying it and how I feel. But its like nothing going to get better with one side communicating, and understanding.

I know I need to leave him. I know I deserve so much better. But I guess I'm to complacent with him.

I need to stand up I need to leave an focus on me at this point but the emotional and mental ties I have to him makes it painful every time I try I cry.

Maybe I can try and slowly detach from him I dont know I need major advice.

P.S Yall there's more bad boyfriend behavior from him. And does all that really count as cheating or is it a over reaction?