Sounds like you, your hubby and sister in law are all a little immature.
Get your own place if you don't like living with your inlaws. Yourself or hubby could get a part time job in retail until something permanent comes along. Stop engaging in petty arguments with your SIL. Bite your tongue if your mil annoys you - until you get your own place.
If you are depressed and need advice on housing please see your doctor. Hang in there.