I have been through something similiar...
I married really young, was not preggo, but married my best friend to get away from my parents (who turned out to be really cool people I learned years later! haha )
I got pregnant and had our son Sebastian a year after we married - I knew not long after that, that I had made a major mistake. Nice guy, really funny - I had
NO romantic feelings for him whatsoever. He was a wee bit lazy, no drive, no ambition, was perfectly content with "just getting by" - That was the major issue for me.
Because of my low self esteem - I gained 30lbs from the pregnancy, gained some lovely stretchmarks all over my tummy, thanks to my beautiful 9 lb, 10oz boy, I looked and felt awful! I was afraid to leave, afraid to do anything on my own.
A couple of years later...I started a new job, lost some weight, gained some confidence and started making big changes. Change #1 - Find a better paying job to support Sebastian and myself. Change #2 - Find a place to live that I can afford and not have to run home to the very same people I had left before. Change #3- Give homeboy the boot.
It was tough, I felt really mean and selfish, but I was 26 years old and knew I deserved more. It was important for me to have Sebastian grow up in a house that was happy - whether it was just with me or with two parents, it just needed to be happy, fun, interactive. His Dad and I didn't really interact with one another - we just coexisted..
It was the best thing I have ever done. My life is completely different now. I have a spouse I adore, who supports me. He listens to me rant about the flipping scale (ok, maybe not really listens, but he nods his head at the right times...), the kids, the dog, my hair, the neighbors
I have had a couple more kids, lost all baby weight and I am back to what I weighed in high school.
It's such a tough decision to make. It affects so many people. If you're willing, maybe see a counselor, do a little 1:1 work and see what exactly you're looking for, or what you want out of the deal. Maybe they'll recommend couples sessions - who knows. Nothing wrong with trying. In the end, it was the best thing for my ex AND I - he is remarried with two kiddies as well and seems to be in a good place.
I wish you the best of luck.