Yes, my wife really liked to hear all about how great my ex -gf was. How pretty, beautiful, intelligent, etc. Actually I had to tell my mother to shut up and never mention the old one ever again! My wife is a super person but it would never extend to me being friends with my former gf! That might work for you but 99.99999999% of the rest that is a disaster.
One piece of advice is to think of the ex as riding a bike for the first times and you fell and got a bit battered and bruised but you got right back on as it was exhilarating to ride! Same with the old bf. Get a new ride!
Or to paraphrase Tennyson -
It is better to have loved and lost than never to have loved at all.
From Alfred Lord Tennyson's poem In Memoriam:27, 1850:
I hold it true, whate'er befall;
I feel it, when I sorrow most;
'Tis better to have loved and lost
Than never to have loved at all.