Help😓

I've been talking to this guy for about 6 months and we've had a close relationship since we first met. He helped me cope with my breakup since we met a couple days after it happened. Shortly after he started to tell me he loved me. I felt flattered but I definetly wasn't ready to say it yet. A couple months went by and I actually started falling for him...I fell in love with him. I noticed that he's been acting weird these past couple of days which led to me grilling him until he finally told me he had a gf and they've been together for a month now...I feel so crushed. I'm so upset that he didn't tell me but I'm happy that he found someone at the same time. I told him that I would leave him alone since I didn't wanna disrespect his relationship but he told me that he needed me. He claims his gf doesn't help him with his problems the way I do. I don't want him to have to deal with his problems alone (they're quite serious) but I don't want to disrespect his gf any longer. What should I do?...