<human>: So yesterday my bf (19) and I (19) got in a small argument. He said something along the lines of "At least I've never cheated." I was extremely confused and respond "What?" He then goes to say "I know you cheated on me." 

I've never cheated. I would never do something so horrible and I would never do anything to hurt him. 

I found out that one of MY friends told him I had sent pictures out and slept around while I was with him. My (now ex) friend has always hated us together and deliberately tries to break us up (although I didn't see it until now). Apparently my bf believed the lies and hasn't trusted me and has worried since September. I explained how none of that happened and how he was lied to.

The problem is that I feel like he still worries about me cheating since he believed I did for 4 months. I want him to completely trust me but I feel like that's impossible now since he told me he still worries.

Can you give me the gist of the text in a nutshell?
<bot>: My "friend" told my bf I cheated when I never did and he still worries even though I explained to him that I didn't.