Boyfriend cheated

So I read his messages on his iqatch, he never shows me his phone or instagram puts it away, or is always in his hand when he has to show a picture. Im not allowed to even touch his phone. So turned out, he has been sexting with 3 other girls, exchanging nudes, he denied meeting them, he says it was before i came to his life. We have been together for 9 months, i love him like crazy. We have a long distance relationship. I went to his city for 2 months, and now for a week. I came to know that all this time he has been talking to them, asking them to meet him even when i was in his city. He says he wanted to tell me but couldn’t because i cant be his friend as i react too much. He admitted everything asked for my forgiveness. I did forgive him but i am hurt, im hurt beyond words. He says its his sickness and i should help him. But how do i start trusting again when i have read all the conversations. Im broken. Please help me.

Update: plus he was using dating apps all this time being in relationship with me, because he wanted to go out and long distance sucks for him. Shes he went out 2 or 3 times but everything was casual.

Do i give him a chance? I am weak. I dont know how to move on. I have had a bad past, harassment, abused relationship and for once i was happy. And i am a surgeon and im 25 years old.