Should I forgive him or forget and walk away?

Ok, so I was dating this guy for awhile and out of nowhere I get a text from him saying that he loves me and all but he loves his ex and needs to be with her. I got extremely upset and went off on him but then I found out it was his friend that sent the text.

Once he got back his phone he got became very upset as well and he thought that I said that we were done even though I never said that.

Next day I see him and I confront him about all of this because I didn’t see any of his texts until the next morning. When I tell him that I never wanted to end it he said that he is so sorry and thought that was what I meant. So that SAME night he got BACK with his ex!! He said he was sorry beaut he wasn’t acting like it.

Before he left me alone he told me, “ I’m sorry, I know that I want and love both of you but I know that I can’t have both so I need to get my head straight and decide but until then I can’t be with you.” I ran away crying. ( btw I’m a senior in high school)

I yelled back at him saying, “ If you wanted to get your head straight then you shouldn’t have gotten back with her because she is making your entire life hell!!” The reason I said this was because I know for a fact that she has cheated on him several several times. He knows it too because he caught her in bed with every single one of his friends.

He left her after he caught her cheating yet again and told me that he was very sorry and should of never doubted me. I told him that it was ok. But the thing is that I really loved him and he was on my mind day and night but I don’t know if I should let him back in my life again.

PLEASE HELP A GIRL OUT?!?!?!