Not sure if I can trust my girlfriend
So, my gf recently took a trip to the beach without me b/c I couldn't get off work during the same week she took a vacation. During the trip she met a guy who she claimed to think was gay. He states clearly on his facebook that he is interested in women and single. Since the trip, she has met up with him locally a few times as he is coincidentally moving to our area. Each time she has invited me to join but each time I was either unavailable due to a prior commitment she knew about or when they went out was too late as I had work the next day so I couldn't go with even though she invited me. She has always said that she loves me and plans to spend the rest of our lives together and would never cheat on me. I try to trust her but because of a badly ended previous relationship I have major difficulties trusting anyone fully and unconditionally. But, after their most recent night out to a bar from which she came home well after midnight, I woke up when she was in the bathroom and her phone went off with a text message from the other guy saying "Good night sexy... PRRRRRRRR" after a series of other messages about how great a time he had. I didn't confront the situation until the next day, but didn't directly say I saw the message or even checked her phone. However, I told her I didn't trust the guy and I worry that his intentions with her are to be more than "just friends". She kept telling me that I had nothing to worry about and got frustrated because she thinks I don't trust her. My reply was asking how he talks to her and if he calls her names like cutie or sweety or sexy since I knew he called her sexy in the text message. She said he never says things like that and if he did she wouldn't want to hang with him anymore, blatantly lying to me. So, when i came home after that conversation, I checked her phone again and she had deleted all the messages from him the night before. My question is, why would she outright lie to me about him using pet names especially "Sexy"? Also, even if him calling her sexy was innocent, why would she delete the message effectively erasing any "proof" that he talks to her like that? I'm really bugging out about this because to me my gf is my entire world and I love her more than anything. I don't know how I would handle her breaking up with me for some other guy and lying to me the entire time. any advice is greatly appreciated.... P.S. we have been having long gaps between our intimate times because she claims to be depressed. She says she is still very in love with me but has no sex drive.