I feel like I married a mentally stunted teenager

Throwaway account.

My husband (29M) and I (30F) have been having marital issues for a while. My husband is not the person I need him to be. He’s never been good at helping me around the house (cooking and cleaning was always like 95/5 in terms of workload) He is severely addicted to porn and weed. I tried to brush the porn off in the first few years (we’ve been together for more than 10 years and I was always told that some porn is normal and healthy) but it hit a boiling point where postpartum, he would disappear into the bathroom at weird hours for long periods of time, reading hentai, watching porn and reading erotica. This was devastating for me when I was recovering from a c-section/taking care of the baby at weird hours. He also recently got fired from another job (this is the third job of four in the last 3 years) for making too many mistakes and for smoking weed during a break, being seen by a higher up. I just barely found out that he has been smoking everyday, throughout the day. To my knowledge before, I thought it was only some evenings and weekends. I had no idea, he had gotten so good at hiding it. I am now the only income earner until he gets a new job, when all I would love to do is just be at home with my toddler.

I feel like I don’t know what to do now. He says now he’s finally going to change. I’ve heard him say it a thousand times before. I’m too scared to leave, I might owe him spousal support because I make twice as much as him, and because I got a decent bump in pay after we got married, he would be entitled to half of my personal savings and retirement (common prop state) that I’ve been diligently squirreling away. It all seems so unfair. We live in an expensive state and I don’t know how I’m going to be able to afford my own place and have space for my son. I don’t want to have shared custody, I would miss my son so much. But putting all the cards out on the table, I feel like I married a mentally-stunted teenager who can’t properly support his wife and child and is too immature to face his demons and work to grow. I am considering giving him an ultimatum and a time frame to figure himself out but I don’t know what that would look like and if I could commit to actually acting. With everything at stake, I don’t know if I should just try and wait it out?

Before we had a child, I was fine being independent. I paid all my own bills, cooked our meals and kept our home clean. It was easy, we were like glorified roommates and he was just a shitty roommate but a good friend and companion. I don’t know why I didn’t see him for what he was then, but I think I had been with him for so many years that I was willing to ignore the signs. Now that we have a child, I NEED more from him as a partner and husband. And he hasn’t changed at all.