OK, so I have a slightly different perspective.
I don't think his reason for wanting to stay is "dumb". There are plenty of women who want to live in the same town as their parents, quite often their mum especially. I think that it's fine if that's a priority and I don't think it's necessarily wrong. I think the scathing comments from PP about him being a "mummy's boy" are a bit shitty actually. It's not wrong to want to be close to your parents.
However, the fact that his mum is spectacularly shitty to you OP IS one of the big issues, along with his refusal to stand up for you. Neither of those are acceptable.
Re the location - maybe he never intended to leave and has lied to you all along. But is it possible that he was deceiving himself too? It sounds like - on the whole - your relationship has been fun and loving. Maybe he knew that if he refused to leave ever that you'd end things, so he fooled himself that he'd feel ready one day. And now there are no more "reasons" he has to face the fact that he just doesn't want to go?
I'm not defending him, just offering another possible perspective to consider. You're the one that knows him OP so only you can tell whether he's always known or whether he just hadn't faced the fact himself until now.
Essentially, you both have similar requirements in a relationship - you both have a place that you want to live. And there's no possible compromise there either - the place that makes him happy makes you unhappy, and vice versa. The difference is you were willing to stick it out for a while. The thing is, it's made you desperately unhappy so it's actually better for both of you to cut the ties - some differences are just insurmountable.
You are absolutely not too old to have children, or to meet anyone else. Or even to do it on your own. You have so many options and you have time.
One day you might be able to look back on these eight years and appreciate the fun you had, and the good times. Not now because you're raging and raw - but when you have a wonderful new life, you might feel differently about whether this time was truly wasted.
Also by the way, he might be lovely company and fun, but he sounds as if he'd be a shit parent. Always broke and sulks when things get difficult. I promise you that you can do better.
Channel your anger into getting things in motion - you have so much to look forward to, and it's his loss.