No cheating, but no trust

This is long so sorry in advance. Basically my boyfriend was going through my Facebook messages and saw that I was messaging a coworker, previously I was messaging about playing some online games but he started messaging me kind of coming on to me, but not really, more just kind of being too friendly.. anyway long story short I deleted the previous messages and he only saw the one where it look like it was ending a conversation but was really just explaining something that happened at work. So my boyfriend thinks I’m cheating on him and messaging other guys and just deleting the messages but I’m really not. His last two relationships he got cheated on and I would never do anything like that but he doesn’t believe me and I know there’s nothing I can tell him to believe me. He also said he couldn’t trust me. We’ve been together for over a year and a half but he says he never can trust anyone ever again but he trust me more than anyone so I don’t understand. The place I’m living I’m literally only here for him. Literally I only have him in the state I’m in, my family is almost 200 miles away but I can’t even go see them for two or three days every few months because he thinks I’m going to go away and cheat on him. I work I come home I pay half the bills literally for him to cook and clean for him I just want to make you happy but I still can’t seem to do that because of a mistake. I don’t know what to do anymore. I just need advice in general.