Just a vent, feeling like a martyr and would appreciate some encouraging words on how right I am and how wrong everyone else is

So the other day me and SO had an anniversary of sorts. He's not really in to celebrating it, but he usually does it do humor me. The last couple of weeks we have hardly had any time together since I work very erratic hours and often on weekends, but for once, on this special day we would both be free for the entire day! Several days in advance I had booked him for the entire day. A couple of days before SS, who's at BMs house falls ill, and BM asks if SO can't have him, since SO works from home and then she wouldn't have to stay home from work. Fine enough, he gets to stay at our place for 2 days to recuperate. I again ask SO "But I have you booked for all of tomorrow, right?" and he says yes.

Then it turns out, that while I was at work, FMIL was over to see her grandson, and when BM came to pick him up she said "SO can have him tomorrow as well!" And SO said yes. So the next day, I'm all giddy about having the entire day with SO, I've planned some nice things, wanted to treat him to a nice lunch and some fun daytime stuff that we never get to do together. Then SS gets dropped off in the early morning, me completely dumbfound.

It't not that I don't want him to have his son here when sick, it's that I had planned things, and asked him several times to give me the entire day, and he didn't even tell me that the plans had changed. I tried to keep a stiff upper lip, I really did. I went by the day playing with SS (he's always in a good mood, even when sick), but I had a very hard time hiding my disappointment. It slipped out that I had planned things, and naturally SO felt bad, but explained that he couldn't say no when his mother had said it would be ok.

So my life is controlled not only by SS, but BM and MIL too. Their wishes always come before mine. Because he thinks I can handle it, I'm his strong woman who doesn't need people the way the others do. Is it too much to ask that I get ONE day, on a special occassion when we haven't spent time together in weeks? No relationship is so strong that it can go on if we don't work on it, don't spend time together, damn it!