Hi OP, it sound like you are exactly where I was a few months ago. My H also blamed my anxiety medication, my mental health, my paranoia etc and made up lots of lies about how his boss needed him in the office more blah blah blah.
I promise you it gets easier. I didn't alter my meds but I did use diazapem 3-4 times to fend off panic attacks. I did sob and wail on my friends and family too.
You have been 'wronged' at the absolute highest level by a man that should have been stood my your side. How you feel is completely normal. He is a spineless waste of space and a disgraceful person. The man you loved is dead, he no longer exists and has been replaced by a rat.
If you can find some fire in your belly please try and do so, if you can't, that's ok too. Just keep getting up, getting dressed and getting through each day. Eventually it won't feel as hard but I'm afraid you're going to have to just hold on tight and bear hunt this shit (you can't go over it, you can't go under it, you've got to go through it).
Use whatever mantras or support you need, stay away from booze, try to stop all the questions your brain has because nothing he ever says is the truth or worth hearing. No good can come from asking him questions, you are simply reopening that wound each time you ask.
Make some plans with the kids if you can but you are doing SO SO well, you are clearly stronger than you believe right now.
We are all here for you and with you.