Are they bragging though?
or just chit-chatting and you are being over-sensitive to it?
its not really fair to expect them to edit their general conversation just because you may be feeling blue.
obviously in certain circumstances you could expect that...such as if someone had just a miscarriage you would expect people not to talk about their pregnancy at the time... but general stuff - its their lives, its what is going on for them, its important to them...why expect them to tread on eggshells?
besides, do you really want your pals to pussyfoot around you, stilting their conversations, waiting until you leave so they can speak freely...?
worse still they could stop inviting you round if they feel you resent their good fortune...
whatever good fortune someone may have, someone else will not be as lucky - so you can't worry about every single person just in case they haven't got something too...
try not to see it as 'rubbing salt in' or 'braggin' or one-up-manship' or anything...and just as your pals going about their lives and counting their blessings...
it is unlikely they are not doing it to rub your nose in it...why would they??
in fact, more people should count their blessings!