Boyfriend did blow with another girl!!!!!

I went through my bf phone📞 while he was asleep and I found a text from a girl I had already told him I didn't want him talking to. It read him: "how long are you alone for" her: "idk" .

I woke him up immediately and started questioning him. He began to tell me that he didn't want me to find out (because I've never done it) but he had been doing coke about once a month for the past 7 months (since we moved in with each other🏡) So I asked why was he talking to her and asking her if she was alone! He said that he had done it with her twice (at first he said once)

and alone because her bf doesn't like them talking either!!! So I hit him a few times and we slept in separate rooms. The next day I questioned him more. He told me he did it with her 3 times now! 😡😡😡 I asked him things like -did he cheat on me (no) -was she in our house (no, he went to her house) -was he ever planning on telling me he was doing it (no he wasn't going to tell me)

So I just don't know what to believe, do I stay with him, we can get over this shit or do I break up this relationship because this isn't the first time I looked at his phone and seen him talking to a girl in way you shouldn't be talking to any bitch if you have a gf!

I do still love him (we had talked a little about getting married💍before all this) but he definitely lost my trust completely for a very long time 😡😔😡😔

I tried calling her to talk because we do know each other but of course she didn't answer.

So what do you guys think I should do from here????