My first paycheck...

Yesterday I got my very first paycheck. It was only $248 but boy was I excited. I put away $80 for my mothers gift for mothers day and I bought my baby girl a diaper bag and had like $140 left but now I'm a little upset because a while back ago my MIL took out a loan in my mans name and promised she'd pay it but of course she hasn't been making the payments he has. Well anyways,he has one more payment left which she promised to pay and the loan people are already calling and threatening. Guess who's gonna have to pay it now? Me. I was trying to save up for my baby shower and money to get my baby girl a car seat and stroller since it is my responsibility. I'm just a little upset,maybe I shouldn't be because he is my man and I should help but goodness I didn't work 30+ hours on my feet while 31 weeks pregnant to pay a loan his mother promised to pay. Sorry I know I sound childish and probably selfish but I just needed to vent I guess. (My bf is currently out of work ATM)