Inconsiderate annoys the hell outta me

So, now MIL is refusing to do the surgery until Brooke and I leave.  She claims to be worried about my sister and whos going to take care of her kids.  I tried to explain to her that my obligations at home were tended to and the ONLY obligation I needed to be worrying about right now was being with my husband when he needs me.  She keeps saying that he will be fine.  I’m not worried about IF he will be fine, I want to be here to make sure he is.  She also says he will be with family, I tried to explain that its not good enough to be with family sometimes.  I was with family during all of dads stuff but it still felt ALOT better to have Stephen there.  Why cant she just appreciate the fact that I do want to be here for my husband when he needs me?  On top of that, God forbid something happen to her Id have to come up with around $800 to fly back out here, I could avoid that if I just stayed here.  Not to mention the fact that my sister would be in NO hurry to help me out, why should I be in a hurry to help her out???  If shes so worried about me getting back to my sister ASAP then why does she not just have it done and let me leave after?  I truly do not appreciate the fact that I am being forced to leave my husband during a time of need.  Nevermind the position she is putting Stephen in.  Its not fair to childishly say to your son "Im not going for surgery until your wife and child leave".  Its all just a bunch of bullshit.  What it all comes down to is she is looking for ANY excuse she can to not have to go.  She has been changing her reason for not going for the last couple of days and now I guess she feels like this one is the best one.  However, yesterday she found out she has to move in the next couple of days so even if she does "change" her mind and let me stay, she is now going to use moving as an excuse.   Im so fking pissed that she is acting this way.  She knows we dont have the money to be here yet she is allowing this to carry on longer than it has to.  Im so fking pissed I could scream.  WHAT A SELFISH THING TO BE DOING!!!!