Boy howdy do I have experience in that domain. 

First is good mental hygiene. You're gonna want to fantasize about What Might Have Been; *Do not let them*. When those thoughts pop up, cut that shit out and think about something else.

Incidentally, that's one of the hardest skills to learn. If it feels too hard or like you aren't making any progress, remember what Jesus said in Luke 23:14, "git gud scrub lol"

Second is self love. Date yourself. Indulge in something you normally wouldnt do. Take yourself out to a fancy restaurant a,d dress to the 9's so you can check yourself out in every reflective surface you see and think 'damn what a man what a mighty fine man'. You can and should fill that hole in your heart with yourself.

Third is acceptance. You already seem to have that one covered. She has free will and her own opinion on things, and her heart made a decision. Fighting that would be dumb. 

Fourth is finding new love. It'll happen when it happens. Be pragmatic about this; Cupid is far more cunning and tricky than you could ever hope to be. Any attempt to influence where and when the fat baby's arrow will land will just slow things down, so don't even try. A lovely human being is in your future, and she'll be coming round the mountain when she comes. No sooner. 

Keep your chin up and you gaze steely. You got this.