We were young, 18, not sure I could have possibly known what I know now. I couldn’t have walked away over something that wasn’t even a known reality at the time,

You're oldest is 13 months, and you're pregnant with your second....in your 30s, you clearly had all the information you need, but you still decided to stay...for whatever reason (sunk cost fallacy? Blind hope that he'd magically change?)

I don’t exactly feel like I’m that much of a catch so he is probably better off without me.

How does this fit into anything? I think you really should invest in some individual and couple's counseling to figure out if you're together for the right reasons.

And yeah... did you WANT to get pregnant, or why did you decide to have a second child if you were already unhappy? And were never overly interested in kids?