WHAT DO I DO?

Okay so, i have a bf and we have been together for almost 4 months, I appreciate him very much but my feelings for him disappeared, not 100 percent but I am convinced that I do not want to continue in a relationship. He doesn't even talk to me, he doesn't text me and he always ignores me, but today... 

He came to me trembling and gave me a letter where he said that he was not good at expressing his feelings but that he does love me.

I started to feel very bad but I don't want to stay where I'm not happy and I don't want it to be even more painful for him when when we end the relationship.

 We are barely and only teenagers...

what should i do?