Birthdays are definitely hard. My stbx always (and I mean always) ends up lashing out at us on bdays. Funnily enough, with him it's our bdays that he spews on. I suppose that's because we make his bday nice for him. For mine and the kids', stbx has the responsibility to do something - and he just can't handle it, hence the guilty spew.
I think your h is having to face a bit of reality - the kids begin upset and angry, and no present or card from you, the W he abandoned.
The fact that OW is now not a secret will also bring its own consequences. He may be proud, but i doubt that anyone else would think well of him - or her.
He seems to be getting a little inkling that things are not going to be like he thought. Most WASs seem to have a little story worked out whereby everything will be fine and dandy. When things don't work out that way - and they feel they are thwarted and losing control of their planned sitch, they lash out - and it's all our fault.
I try to see my stbx's fury as a sign that he is struggling. And if he doesn't struggle, he's never going to look for answers (outside of blaming me) for the position he's in.
Focus on doing what's right. Protect yourself and your kids. I know you'll get through this. We're all here for you.
