I say get out now.

Best case scenario, he is unable to cut those apron strings and be a real man who doesn't run to mommy at the drop of a hat. (Even this is enough to RUN from.)

Worst case scenario, its incestuous.

Either way, get out now. Your future mommy in law has no boundaries. You'd have to watch her like a HAWK around her kids to make sure she wasn't.....yeah, bad thoughts that shouldn't be in your head. Get. Out. Now.