*UPDATE* "Think my boyfriend cheated on me..."

Amy
Well, he did. 
On New Year's <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> I found texts and fb messages from 3 different girls. He had fought with me constantly. 
The next day I broke up with him. The day after that, he was taking pics with a well known drug addict who has hep c. They were all cute and cuddly on the couch. 
I lost my shit. I know we were broken up, but still, that was done to hurt me. And I have two children, this is not the way to deal with things. 
So the next day he begged to talk to me. I did. 
He told me he never touched them but he did see how he was emotionally cheating. 
I told him we aren't getting back together for a very long time and he has to prove to me that he wants me and the kids. I made him take a drug urine and hair test. (He was also a past drug user but has said he's been clean for 7 years) 
He has to do std screening. All of it. 
Then come to find out his ex (one before me) has hep c and might've given it to him, which then would've given it to me. 
My doctor that I talked to said it can be transmitted through blood and sex. So I'm a little freaked bout that but it's not like I can be mad at him for something in the past. I'm just mad about now. 
He's given me all his passwords, but when I logged into his fb account it locked him out of it for a duration, and somehow deleted half his personal messages, I know I didn't do it so I told him to write to fb. 
I don't know what else to do. Anyone else give me advice? I told him at this point I don't care if we get back together or not, if he wants it, then he needs to prove it to me. 
Still can't believe he went to known drug users...seriously...
*UPDATE****
I know I haven't made some of the best decisions, but I also know that I'm not making horrible decisions either. And yes you can write the help center on Facebook to find out about deleted messages. After researching last night, a lot of other people have had the same issues after having two different devices logged in to the same account. 
The girl who has hep c that was his ex was a few months before me. I have been tested since then, but A, didn't know that she has hep c because neither of us were notified about it. And B our hospital here only checks for gonorrhea, chlamydia, and trichamonosis. I have asked them several times to test me for everything and that was all they tested me for (I have unrelated health issues and when they arise they also test me as well) 
Wen you're in a relationship, you generally trust the person that you are with. If you don't, something is wrong right off the bat. 
His previous drug use was 7 years ago. It wasn't like it was yesterday and he has been tested as well several times (you can look up medical records within our hospital web site, and he has shown that to me.) 
I was there when he wrote his exs mother, I saw the messages. She is beside herself thinking that she told us. 
Also, when you test for hep c, there is a test that tells you how long you have had it. Not going by days or months, but whether you have had it for a long time, or a short time. If it comes back as a short time, then yes we are done. 
My kids are his children. I do have to see him. 
I'm not trusting. Not since I have found everything out. Everything was fine until a month and a half ago and I don't know what has changed. I do love him, and I know that there are a lot of stories about cheating partners, but that we're given second chances and have worked. It's really hard to go back, and to be honest I'm not back there yet. There has to be a lot that changes, and I'm not a 100% that it will change. 
I know a lot of you think I am being stupid, but to be honest, if this situation happened to you, what would you do? What would you actually do? I always thought I would say "peace out", which I did, but have considered down the road that a second chance might be in store.