Cory, I didn't get a happy birthday wish from my husband when I turned 40 a few months ago. I don't know how they can be so neglectful. I feel the same as you about my husband - still love him despite all the bad things he's done and wishing to understand what happened.
I hope you still managed to enjoy your birthday with other special friends and family. I hope the coming year brings you clarity and healing. I hope you'll understand everything someday. I'm hope in a few years you'll be able to meet up with your wife and she'll explain everything to you.