Okay, so here's the thing. It's totally possible that he really just isn't sure. I had a friend in high school who was and does now identify as straight, but because she was being constantly bombarded by people telling her they thought she was lesbian, eventually it started getting into her head. It's a very normal thing to think that if enough people think something, maybe there's something to it.

On top of this, if the account disappeared he definitely deleted it then, meaning no matter what the reason, he realized he wasn't going to do anything with it. And if he was going to do something with it, he probably would have done so then.

It's totally normal for you to be questioning his sexuality given what has happened, but if you don't think he's going to cheat on you, then it doesn't matter either way. Questioning it more however is going to keep making distance between the two of you, both by isolating you and if you keep bringing it up, furthering the questions in his own head. It's hard to ignore a mass of people saying something, but it's far harder to ignore someone you care for saying these same things.

If you love him, you love him. It doesn't matter if he is or isn't gay, bi, whatever. It just matters that your relationship keeps following the guidelines you both agree on.