@legoisaws8om I know, it's like trying to retrain your brain- but honestly the relief I got after putting down that boundary and listening to what I needed- was a total weight off. Mainly because I'd started to worry about how often they'd post, would they post more pictures etc. So just like @doodledeedum said, I needed to give up worrying about what other peoples comfort around me.
It sounds like you were more comfortable with a one to one with your friend, could this be an option with your SIL? Say that youd like to celebrate with her but at this moment you don't feel able to do so in a bigger group setting (or whatever you feel like at this time).
Or you can tell this internet stranger to shut up, I'll respect that boundary too! 😂