I’m sorry you are hurting on a yearly cycle. Since you are reaching out for help you are taking a positive step. And congrats on getting sober. Though the title of your post is about your marriage, the advice I have focuses on your second paragraph.
If you are stable your children will experience some stability.
If you are angry at all men your son will be affected more by that than by the amount of females he is around. He will be a man one day too. Your attitude towards men is going to be a part of him.
If you want to work, what is holding you back? Take steps to fix it. I know it will be hard but even if you think you’re unsuccessful now, after a while you will notice you accomplished more than just existing. It just takes longer than we’d like.
That is all you. The hurt over the loss of your best friend will still be there but all of the above could be worked on even if he was around. It’s your part.

The other thing to consider, not sure it’s advice, but I’ve done it myself, is to move somewhere warm. Where is he going every winter? If it’s not the weather maybe it’s the holiday circus he can’t take. Why would he keep coming back after that if he didn’t want to be with you and with his family?