Sadgranma....I feel so sorry for the situation you're in, and sorry for some of the responses you've had on here.
I was in the same situation a few years ago...my son got with a girl who had a child, and we babysat, bought the girl things, took her out, etc. Then, my son and the girlfriend had a baby together. I was thrilled as it was my 1st grandchild. The mother never once let either my husband or me give the baby a bottle, hold her, change her, babysit, push the pram, etc, Not once. Like you, we don't smoke, have a clean home, and are good people. We used to be invited to go round to their house once a fortnight (fair enough), but for one hour only. That all continued until they had a 2nd child. They split up when the 2nd baby was a year old. Then, my son had the children every other Sunday. Only then did we get the chance to give the baby a bottle, change a nappy, push the pram - the 1st child was 4yrs old by then.
Now, we see both children every other weekend (when my son has them both) and we go out with my son and his girls, go to parks, for meals, etc.
I hope that things get better for you, Sadgranma, BUT you must maintain a good relationship with your SON, above all else. He is pivotal in all this. Let them call the shots, and try not to be seen by your DIL as being critical or interfering. Good luck.