I feel like I'm going mad. DP and I have been having some issues for a while (unrelated to this). We've been trying hard to work on things but recently, I've been feeling jealous of his relationship with another woman. This woman is much older than my partner, so I don't know if I'm being ridiculous. I need some insight. So they were friends for a little while but recently they've grown closer and massage every day. Good morning messages etc. He's sat next to me messaging her before so I've caught glimpses. Anyway today I just felt something was off so I went down his phone and saw good morning message with a kiss emoji. Then I scrolled up and felt sick because he was saying how he missed her, and a nickname she was giving him made him "feel mushy 🥰". Comments about how she must want a hug from him etc. I kind of exploded and told him how I felt about this. Obviously I betrayed his trust by going down his phone which I will admit but I would have never known he was crossing a line otherwise. He claims he only sees her as a friend and was not flirting. But is he being truthful?? He seems genuine but I would never dare to talk to a male friend like that. I don't know what to do as I don't feel I can trust him anymore..