For 6 years or so, my FP has been my ex. I have tried to ignore it and date other people but it never feels as good as the highs I felt when I dated him (but the lows were EXTREMELY low). Over the past year we became close friends and all the feelings came to a head again. Problem is, he's dating someone new and they're getting serious and since I'm his friend now naturally I end up hearing about it - admittedly not in great detail, but in enough detail for me to fill in the gaps with horrible visions of her being literally perfect, of him having the best time and the best relationship EVER with her, and of me being some ugly stepping stone in between. 

I can feel him pulling away from me somewhat, in the way that people tend to pull away from their friends when they're in the honeymoon phase of dating, but it fills me with anger and sadness, because I want to be my FPs favourite, I want to be top of the list, and before he started dating her we were so close. I feel like I don't matter to him now, or matter at all. 

None of this feels healthy but I don't know how to get past it. I hate myself.