I can speak out of personal experience, and this has nothing to do with my current situation because since the beginning I promised to myself that I wasn't going to harbor any ill feelings towards her. So far, I haven't or at least I stop myself when I start feeling them.
My personal experience was with an old ex girlfriend, she pretty much dumped me for another guy, got engaged to him after a couple of months and got married 1 year after. I really resented her for that, to the point that I hated her guts. I promised myself that I was never going to love a woman again, that i wasn't going to let anybody play me like that and I sadly succeeded for a while.
I spent 2 years without dating a person, I didn't trust women and all because one woman treated me like that. Who was at fault for my own loneliness? Me. After a while I started to understand that keeping ill feelings towards somebody doesn't help at all and in this moment whenever I remember about her, it puts a smile on my face because I remember all the good not the bad. She is even a mommy now, and I am glad that she had good luck with the guy she married, honest to god
Same goes to my stbx wife, I love her and all I want for her is to be happy and thrive in her life. The fact that our marriage didn't work doesn't mean she is a mean person, but that we were not compatible, as a matter of fact she is really nice and sincere woman. She will always have a piece of my heart for that. Think about the good, forgive the bad, I am pretty sure than your soon to b x did nice things for you as well and sometimes they are even more than the bad things but humans tend to remember the negative more than the positive.
The more we let go with love, the faster we are going to get our life back and our happiness, and who knows maybe the real one will be around the corner