It looks like he has made a choice and is working with it, has decided he can abide by his parents' 3 month idea; you probably should work with that too? It looks like a bit of a compromise; he is doing what his parents want but has come to live at your parents house.

I would focus on him and follow behind him (I do that in crowded restaurants; my husband is a big man so I get behind his back and follow him out the door :-) and stop crying and start smiling and planning, be "with" him in spirit and present a united front to both set of parents.