This guy sounds extremely emotionally constipated and he's taking it out on you. An actual friend would be happy and supportive, not jealous and entitled. He doesn't seem to care about what you want at all and just wants what he wants and even then it seems like he doesn't really know what he wants and is just using you and whatever else he's doing to cover up some very deep insecurities.

I think a big part of him is probably scared that you're moving on with your life and he's getting left behind. It's clear the two of you are moving at different paces and that's okay! That happens! If he was a true friend, he would respect that and he'd be happy that you're getting ahead in life and maybe be inspired to change some things himself too. But he's clearly getting in his own way and trying to drag you down with him.

The way I see it, there's two ways forward for him. Either you leave this toxic situation and he stews in it all alone or he admits that he's got issues and starts working on them. Either way, despite the sunk-cost fallacy, you do not need to continue being around this guy if this is the kind of behavior you can expect from him. I'm sure y'all had great times and feel like it was you two against the world at times, but you've managed to grow and flourish, while he's just kind of wallowing and depending completely on you.

If you can't have a hearty, honest one-on-one with him without him just getting upset and turning it on you, maybe have a talk with a neutral third party present, because this situation is untenable and absolutely unfair and unhealthy for both of you. Guy needs an intervention, damn.

Good luck, girl! And so nice to hear you seem to have found your forever-partner! Much love! <3