Kinda upset! Ok really upset! Just need to vent!

So my co workers/friends invited me to lunch next Saturday I was so excited just to have a lunchouting without my 3kids lol u know some me time before Jax comes, anyway I ask my sister if she can babysit and she's like I can't that's ur baby shower day I'm like what?? She laughs oh oops it's suppose to be a surprise I'm going to that outing so is blah blah blah and I literally cried!! She's like I'm a bad liar and blah blah Idc u could've made something up I would've understood ya know! Now I feel bad, I know the girls have probably planned this and worked hard and it's supposed to be a surprise and I need to act surprised cause i dnt want it ruined for them! I have been so hurt and crying!!!