Welcome to divorcebusting.com. I just happened to peak at the board and saw your post and wanted to respond to you.
I'm really sorry he missed your birthday. I hope you found happiness on your day anyway.
It really is not a good idea to contact him. I understand your internal push to do so, but it is more likely to push him farther away from you than draw you closer. When the OW is gone....it MIGHT be ok to test the waters, happily and pleasantly.....and honestly, we'd want to know more about your situation before offering that advice.
Find ways to make yourself really happy. You deserve it, need it AND it makes you MORE ATTRACTIVE. When it bombs out with this OW, you want him to be irresistably drawn to YOU.
In the meantime....why not tell folks here more about your interactions with your exH.
sg
sg Love is PATIENT, love is KIND, LOVE never fails / DB since 2001