Ohoh. This is huge. In any relationship the partner should come first. This is a very big sign. You need to put your foot down with your boyfriend. Not only that you come first but your expectations of his mother's involvement in your lives.

My first husband was so attached to his mother that he went over once a week for family dinner without me. Throughout our entire 8 year relationship she came first and stuff like this continued. It made for a great deal of difficulty. My cooking wasn't like his mom's. If mom said this or that (ie. it was disgusting I breast fed) then that was the way it ought to be and we fought if I refused to change. She was to a great deal the reason we broke up - he became obsessed with what mom said about me and it grew to be quite emotionally aabusive.

I am truly sorry, but you need to find a way to nip this in the bud. If you can't encourage the change now it will just continue.