Going through your partner's phone in this situation, you were invading their privacy for sure.

That being said. This is probably a "you" problem in terms of how do you feel about this? Is your partner watching pornography a dealbreaker? Is the amount of pornography he's watching unhealthy?

Collecting hundreds of porn titles... I don't know. Seems weird to me. Could be a "joke collection" or something. I don't understand why he wouldn't just save the files or links, but the titles.