I feel your pain, Medusa. This has happened to me on several occasions over the years, but by FAR the worst offender was by my uncle who sprogged late in life. "Uncle Willy" never attended any birthday party of mine that I recall neither before or after he was married. He never gave me a Christmas present, sent a birthday card, or even called me or wrote very much for that matter. I was a teen before he had any kyds and of course after that, everything was "different". He expected gifts for all of his brats because by the time he had the 3rd one I was nearly 20 years old. I basically drifted apart from him and his famblee (on purpose) and didn't hear much from him UNTIL a few years ago when his son sired the golden grandboybrat.
Although I lived 3 hours from them at that time, I received an invitation to the grandboybrat's first birthday party and judging by the card it was going to be complete with caterers, hired clowns and a Barney, and a fucking rented pony. Oddly enough, it actually had an RSVP, which I thought was RIDICULOUS. What, had he become a movie star and I had missed it???? I didn't respond at all and apparently that upset him based on what was reported back to me that he had said. I was nearly 40 years old, NEVER had gotten a card from him for birthday or Christmas, NOR had he ever bothered to send my step-kyd a birthday card and she was around and in our famblee since ages 2-10, at that time. Yet HE thought that I was supposed to make arrangements to drive 6 hours round trip to come to a SECOND cousin's first birthday party? I don't think so.
Apparently, my lack of interest in his grandsprog has basically caused him to completely break what contact and ties that he and I had at one time which was occasional letters and phone calls. This is a form of breeder mentality where THEY are invisible during our childhood or other events throughout our lives, which are special or important to us, yet the MINUTE they self replicate we are supposed to drop everything and make arrangements to be present and shower them with money and/or gifts. I think that this is the HEIGHT of selfishness and it has taken me some time to convince myself that, NO, this isn't ME being an ass like they are making me out to be, but rather it's a normal response of someone who refuses to be taken advantage of and play their silly games. I absolutely will NOT be guilted into doing it no matter HOW many times my mother says, "Two wrongs don't make a right".