My husband was reluctant to join Facebook and when he did, a friend he knew started sending him messages through it with those things that come up and a lot of them are those memes (do I have that right?) of women with sayings. So if I walk past his screen, those can be up - but he's not looking those up - his friend sends them. Does my husband send them to him? Doubtful. Not my husband's thing. He might chuckle the odd time if the saying is clever but the guy is kind of sexist (not a close friend of my husband's). *I should add - they're not naked, and they are supposed to be a joke.
My husband usually closes the screen because we have kids - not because he knows I'd be jealous. I am more grossed out (I find them sexist).
Erotica being shared by two guys .. if that's what it is? Seems a bit odd. It's the sharing part that seems strange. I would assume your husband could look up his own. Who knows. I don't think that's something my friends' husbands do .. other than these meme type things on Facebook, etc.
If it's the looking at pics that bugs you - I think (some) men (and women) have been doing this forever, so no, I think I'd let that go - unless it was actually someone he knew. Then that would be a problem.
It's fantasy right?
As for your weight, and him making comments (do you mean you feel it's passive aggressive? he's trying to get your attention by making comments about others?) then that's an issue. If you're overly-sensitive, which I get if you're bothered by it yourself - then you need to work at letting that go. If he's being a dink, you have to tell him to stop making comments about people who have weight issues - because it's unkind. Period.
Or just say "I don't want to hear them".
Hope that helps. It's hard when there's a past history. I can imagine you must have doubt creeping it. Remember, that's him - not you, so don't torture yourself by making that about you. It wasn't. That was his crappy character, not your own. Most men cheat because they have low self esteem - it has nothing to do about your weight or your inner/outer beauty. Hugs :)
ETA - my husband has never saved/downloaded pictures to his phone.