I must toughen up!

One of my sons moved house last week. I had my DGC for one whole day, part of another and offered to have them at any time. I didn't actually help with the move as I have a physically limiting illness for one thing, plus my still working husband ( not my sons father, but he has a good relationship with him)had a week off, planned long ago before the move, to catch up on jobs at home. My son had a real go at me saying it was a very important day in his life, and I should have been there to help them move in! To make matters worse ( in his eyes) I had a new educational class booked for the same day, something I haven't tried before, booked long before the move , and I didn't want to miss the first class. However, son and DIL are clearly cross with me, and just to finish things off, DILs parents are there 99% of the time, cleaning, mending, painting, repairing, child minding etc. It's been made very obvious how wonderful they are, particularly on the dreaded social media. I feel a bit upset, but guilty at the same time, and also made to feel selfish. The sensible side of me tells me to ignore it and toughen up, as I know I will soon be called on if child minding crops up, and husband stresses we have our own lives to lead, and also has pointed out how little son helped me at home. I am annoyed with myself, but hate the feeling of a slight rift. Son has been ok ish when he has texted, but it's frosty, not his usual self. I find it frustrating, that after all the things I have been through in life so far(same as lots of us) family still cause me 90% of my negative feelings...situation normal?