Fiancé got caught lying: Advice?

This is gonna be long, but hang with me. So, my fiancé has trust issues (from his ex, which so do I, but I don’t hold my trust issues from my ex against him) anyways, he is constantly accusing me of talking to other men, or saying I find other men attractive, and that I’m gonna leave him, etc. However, I don’t talk to other men or anything and I have NEVER done that nor still haven’t and won’t because that’s not who I am. He always tells me he wouldn’t cheat on me, I’m the love of his life, and I’m the only female he finds attractive, he would never look at another woman like that, etc. Well, I’ve always been told someone who constantly accuses you of things, must be hiding something. I’m not the type to go through someone’s phone, but I had about enough of him accusing me of things, so I told him to give me his phone (which he did willingly) and I was going through things and saw he like videos of women that were half naked and were teasing. Not just one video, but multiples. I obviously got mad and asked him about it and he of course said “I don’t know how that got liked”. Of course I called him out and told him he was a liar saying he never did anything cause I would say stuff that he’s done (before I knew he really did cause I just had a gut feeling) and he just kept saying he’s not done anything. Well, then I go through his pictures and he had a VIDEO SAVED to his phone of a girl with a vibrator. That sent me over. I confront him once again after he said he wasn’t gonna hurt me again. His excuse this time was “I didn’t save that, I’ve never saw that. I got a text that was spam and it sent me to that link” okay one, where was the text? He couldn’t show me, secondly, even if it was a text and he clicked on the link why would the video save to his phone? I’m just really confused on what to do. He’s lied to me saying he only looks at me, he’d never hurt me, etc. if that was me who done that to him he would’ve been done. Is what he done counted as cheating? I need help. I’m so lost on what to do. I don’t know if I can ever trust him again. :pensive: oh and I should add that we have four kids. Two are mine from a previous relationship, one is his from a previous relationship, and then we have one together.