Far out! Do your parents know your sisters are being so difficult? That must be tough. I think here, you just have to decide that you're going to act with integrity and maturity, having nothing to regret, and then after time (and the waiting will be tough) people will realise who has been well behaved.

It will take a lot of biting your tongue and setting a good example though - I don't envy you. But you will need to practice that for your kids anyway, as they watch how you react to your sisters' bad behavior.

(By the way, I had my first bub at 22, as have many many others and it's a fun age to have kids. )