First off, I am so sorry you feel hurt and unappreciated. It is very hard when you feel like all the time and effort you put into your family does not get recognized.
I had a mini melt down of my own on Mother's Day. My family totally FORGOT. I truly and honestly could care less about gifts, but saying "Happy Mother's Day and maybe making an effort to makes some breakfast or whatnot would be nice

This year, they forgot and DH as well as both teens were particularly "needy" wanting help with things hat morning. DS was making waffles and kept asking for help fining things he ought to have been able to rummage out on his own--and I assumed he was cooking for ME. Well, I came out of the shower and he was sitting eating the ONE and only plate of waffles he had made--just for himself, and I burst into tears
Sigh.
So anyway--before I start asking questions, I DID want you to now that I really and truly understand those hurt feelings
I just turned 50 in the past couple of days and my wife and kids(22, 17, 15) don't understand why I think they don't put much effort into gift giving. My combined Fathers Day and 50th Birthday presents included a bag of miniature peanut butter cups and a bag of mini mint Milano cookies. I've already told them I will never invest more than 2 seconds purchasing a gift for any of them! My wife honestly stated that I am needy if I think those gifts are lacking. I somehow thought that 5o might have been a little important.
You say your gift "included" peanut butter cups and Milano cookies. Was there more? Had they put together a little basket of things you like? Are peanutbutter cups and mint cookies things you generally DO particularly like?
I am just wondering if there WAS thought behind the gift that maybe you are not seeing through your initial hurt of it mot being what you were expecting/hoping for.
In our family, small treats like that, that you know the person really likes, would be considered a nice gift.
Also, did you talk ahead of time about wanting 50 to be more important/special? Has your wife turned 50 yet, and you made a big to-do of that? Did you make big to-do out of 40?
DH and I both turned 40 on our last birthdays and we did not do anything more or different than for any other birthday--and it honestly never occurred to me to do so. I would not think to do it for 50 either, unless someone told me ahead of time that they wanted me to
If his was more or less the norm for birthdays in your family, I am not sure it is fair to be angry at people for not knowing you wanting more for 50, unless you were very up front about your wishes early on.
My wife was offended when I said that I would set all future expectations to zero. Sorry, they spend longer thinking about where to eat than they did on my gifts.
Well, honestly, if I were your wife I would be offended too. It sounds like everyone was there (not always an easy feat with the ages of your kids) and a gift was gotten. Was the decision about where to eat them taking you out for your big day? If so, that again is something, and they apparently put thought into where to take you.
Basically, they all got together and they DID spend time with you and they DID try to do something to make the day nice, and you told them that what they did was not good enough and was in fact "zero"--that is pretty hurtful and I can understand her reaction. It is not like there was no gift, no meal out with the kids, no notice of your birthday at all.