I know in terms of logistics what I need to do. I more so just need advice on not letting my guilt for his situation stop me from doing what’s best for me.
Thanks for the update, and I think all of us felt exactly the same way.
Here's the thing though. Your husband is responsible for himself. You're responsible for you. And no matter what you do from today forward, it can't change the fact that he has untreated mental illness. You can't save him, you can't convince him, you can't do anything in that regards.
So where does that leave you?
Option 1, you stay and "deal with it." You're not happy, he's not happy, but you keep doing it because that's what you've always done. On paper, it looks better for the kid...but that's not always the truth. A happy, mentally-stable mom is what's best for the kid.
Option 2, you leave and your husband resents you for it. But here's the thing, he resents you now...and you resent him. Where's the downside? He may actually get worse mentally, but that could also be the thing that pushes him towards therapy and recovery. Heck, leaving could technically be the one thing that could actually save the marriage.
The guilt you feel is not directly tied to your situation...it's tied to years of mental strain in a troubled marriage. It's familiar, it's comfortable, even though it makes you miserable. If there was even a 1% chance you could "fix him", I'd be the first to tell you to stick it out. But you can't fix him, nobody can until he's personally ready for real change.
I hope that helps!