Hey OP, I'm pretty late to the thread here but I didn't want to not pop my own experience down, as a form of hope.
I married at 23, and had a baby at 24. He left me on my 26th birthday because of the reasons you've indicated in your post. Both working full time but he earned marginally more which therefore meant he was better than me, finances split 50/50 with me doing 100% of the child rearing, housework, life admin and so on. Was constantly chatting up women online and complaining about his wife's lack of interest in sex (do we wonder why??). It was awful, but he left me, and made me feel like I was a failure.
We were renting which I took over and he moved into his parents, I had to claim universal credit just to cover the bills, he only saw DD twice a month despite living on the other side of the street. I felt like an absolute failure, like I'd never find my feet again. I was left with around £15k of exDH's debt that he'd taken out in my name.
Over the last few years, I've found my feet, I have a new job that pays well and I absolutely adore it, I've bought myself a nice car to get me and DD around, we've been on a tonne of holidays UK and abroad, and now we joint own a house with DP, who DD absolutely adores.
We split finances proportionately as DP is a high earner, we split household chores, life admin and parenting equally, and we have a cleaner which allows us to make the most of weekends as a family.
I'm incredibly content with my life, ex's debt is paid off, life stresses are minimal and I'm happier than I've ever been.
Moral of the story - it's scary as fuck now. But I absolutely promise you that you will be better off without him, you will find your feet, you and your DC will live a wonderful life together. Things always get better, stay positive and know that better days are coming ❤️