The kid thing is only half the issue for you, but your fighting is pretty much his whole life now during his formative years. The child is THE most important issue here.
Feel free to have all the irresponsible fun you want, as long as you don't enter into adult responsibilties, like children, leases, etc. It was extremely irresponsible to move in with someone you've dated a few months, but at least you understand it now....you don't want your own issues to impact more innocent children in the future.