Weird triangle relationship with guy who I believe is still in a straight relationship.

I met a guy on grindr in my university area. We started chatting and eventually met over coffee and hit it off really well and kept things light and friendly. We're both pretty discreet, me having only a few friends knowing and him not out at all.As we got to know each other more and more, he eventually dropped the bomb that he was still in a 4-year long straight relationship. I immediately felt that it was a bad idea to get involved with the guy but he assured me the relationship was almost non-existent between them. He loves her as a friend but he cannot do much more than that. We decided it would be best to continue being friends with another. He is a really cool guy and it was great to have someone to talk to about my issues that my straight friends couldn't understand no matter how much they tried. I learnt a lot about his anxiety and depression issues and we really understood one another. He also explained he would be leaving early next year for work abroad so being anything more than friends would not be good for us. He even met my friends one day and he knew they knew he was gay which is extremely brave of him I'd say. He basically came out then didn't he?As time went on he messaged one night telling me he had come out to his girlfriend. He explained to her he had hooked up with numerous guys, done things and believes he isn't interested in females. She however believes there is still hope and thinks maybe once he is off his anti-depressants he will have his sex drive back for her (He used the pills as a reason for a lack of erections and sex drive with her). So technically I don't believe they even broke up?Anyway, we continued our friendship and we spent some nights watching movies and I'd stay over with him and we'd cuddle. Thats probably when we started becoming more than just friends. We eventually made out and jerked each other off. We'd go for drives, coffee, study together etc.The other day he posted a photo of him his "girlfriend" basically implying that they are dating. I confronted him about this as I felt like I did something wrong (feel like a slut). I would never have kissed him or even stayed to watch a movie if I had known that. He said she posted the photo, she is controlling him because she thinks he is seeing someone. He moved out of his flat into his girlfriends (still not sure what they are) for the remainder of his time around campus before he goes abroad. He mentioned to me he will be leaving early next year and she would be joining too (YES HOW CRAZY). He said he is so into me yet there is too much going on at once to do anything about it.Now I definitely know I like him and have a soft spot for him. I think I will be able to get over it in due time. However, I feel like I should be trying to help him understand how unhealthy it is to still be attached to this girl and how it is going to hurt both of them in the long run.I don't know how to feel about this. I try not to talk to him but he is all I think about. I don't know if its because I really think he needs my help or I've fallen for him. I have no idea what to do either? Talk about it all and try and help?Ignore and move on? Its all too difficult for me.TL;DR: Having a light relationship with someone who is still dating a female who knows about his sexuality. Need advice as what to do.