Sending you hugs Must Survive!!
Right now, how you see yourself and how you validate yourself is through a distorted, cracked and foggy lens. Infidelity and his OW #2 or #3 or #4 or whatever have nothing to do with you and have nothing on you.
You, my dear, were faithful in a long marriage which I'm sure had it's normal ups and downs as all marriages do. You are making the most of this shit sandwich you were served. Please reframe this remark "Am I so horrible that he could find at least 2 other women who he would rather spend time with other than me?" YOU are ABSOLUTELY NOT horrible! His actions show how pathetic and selfish and entitled and shallow HE is … NOT YOU!
Continue to heal, Must Survive! You are so worthy! And yes, take back your birthday!! My stbx also did not acknowledge my birthday ~ I had to beg for a card. This past summer was the first birthday without him and my mom threw me a small surprise birthday party with a Hello Kitty theme. It was so wonderful being surrounded by family that loved me. From now on, I will do something special for me on my birthday because WE DESERVE IT!
You may not see it yet but you are so much better without him.