Husband of 3 months cheating with prostitutes

Sorry if this is long and rambling. I just feel like I have nowhere to turn. I’ve been with my partner for 9 years. We were married in June and in August he started sleeping with a prostitute/s. He started taking cymbalta in May and was acting a little weird around the time he started sleeping with her (picking fights, irritable, mood swings, suggesting we see other people). He was always very stable and dependable before this. He even still judges a family member of his for stripping years ago.

At first I found weird written notes to himself in September that said to tell “m” stuff. The notes were sexual in nature and I asked him who he was referring to (I pretty much knew he was cheating or talking to someone behind my back at this point). He tried to say the notes were things he wanted to discuss with his mom. Again, I knew he was lying but wanted to try and work through it. Then I looked at his phone a couple of weeks ago. Almost every 15 minutes he was dictating notes to himself about his feelings for this prostitute. The notes were sexually graphic and he even mentioned he had never felt that way about anyone before. He also mentioned he had stopped sleeping with other prostitutes, so they could have oral unprotected. He also discussed going down on her. There were also tons of extremely hurtful things he said about me (eg I “gave” him my 20s and he feels guilty leaving me in my 30s bc “women don’t age well”). There were also some off the wall notes about things that never happened (me cheating on him) and things that were in the future that couldn’t have taken place yet (me refusing to go to a concert that was next week).

When I confronted him, he admitted to sleeping with her 3 times and that he had been planning another meeting that week. He said he never had unprotected sex and that the other prostitutes were just part of a story in his head. He said the cymbalta has given him racing thoughts. When I told him I wanted to see everything in his email, he freaked out said to “just divorce him” and that he was going to kill himself.

I just have no idea what’s true and what’s not. Some of his notes are lucid (worrying about giving me a disease). Some are just crazy. He said he’ll get off the medicine and “spend the rest of his life making it up to me”. It’s such a mindf**k, I don’t even know what to do. We’ve gotten tested for STIs and have therapy next week. We don’t have kids, so I wonder if I should just jettison this whole relationship I’ve given a decade of my life to.

Any thoughts would help. I can’t really talk to friends and family bc I don’t want them to judge us if we stay together.