So sorry you're being treated this way.I can think of nothing more painful than being excluded from seeing GCs as they grow up.I'll be honest my own DD rings to be' talked down' when her partner's mum has been round.But she does make comments,ignores requests for what to feed DGD ,even dressing her in clothes she thinks are more appropriate than the ones DD leaves out .Plenty of reasons to get annoyed!You sound lovely and as if you've been very aware of not encroaching or interferring.What annoys our DD the most is his mum barely even registered her sons existence until they had a baby,very focused on her much younger son from a 2nd marriage,but now expects their schedule to fit in with hers re visits.
However,DD accepts it's his mum,and her DDs Grandma,and from day one I have said don't leave her out.Its hard for mums of sons sometimes.I'm shocked at some of the threads I read on Mumsnet where some DIL s take umbrage at the slightest thing,almost looking for an excuse to cut off the MIL and keep their family unit very insular,or just including the chosen few.
You sound to have been so supportive towards your son through his education, and that's a huge help towards a house.Of course it's never a given that when you give you get back.We've helped all of ours through uni ,further training and a small amount towards houses.Not as generous but we do have 3.DH has always said he'll be happy if they just want to come and see him from time to time when he's an old man.Hopefully we've led by example by being there for our elderly parents.
What is so sad is that even doing all the right things as parent,trying not to interfere but you still get ostracised because it would seem a small number of women feel unable to 'share ' their DHs. I find it unfathomable. Even if it's a case of the son visiting his mum with the DC on his own.Then the DIL gets some precious time to herself, and grandma gets to build a relationship.
I really hope your son rethinks things and gets in touch.In the meantime I hope you have good friends and neighbours to lighten some of the sadness .