Should I stay with my husband or should I leave him?

Okay I am apart of a blended family my husband has two daughter from previous marrage I have a son from a previous marrage my husband and I have a child of our own. We had a fight last night that stemed from a visit to mcdonalds where he said he wanted to buy the boys a mc flurry well our youngest son was wiggling his way out of his car seat so my husband told my oldest to put his brother back in his seat well to do it my oldest had to take off his seat belt well hubby makes the order at the drive thru and my son didnt want to get out of his seat while we moved on to the window to pay so he sat there waiting til the car had stoped at which time we was asked to move up to wait on our order well my hubby turns and sees that my son's seat belt was un buckled and he started in with his nagging. My son was asked why his seat belt was undone well my son didnt reply so hubby says you dont get your treat til i get an answer so my son gives him an answer the answer wasnt good enough. KNow keep in mind this is how all of or outings end up unless its an outing with his girls and my sons off with his grandparents.well we got home and our youngest son did some thing hubby didnt like so he started treating him like he didnt want anything to do with him. I finally blew up. I Have sat here and watched his youngest daughter misbehave and my hubby would hold her and comfort her after he would correct her behaver but when it come to the boys he acts as if he doesnt like them. he tells me that our youngest gets on his nerves because of his crying and says his kids never use to act like that. well Im sorry but all babys cry and fuss every now and then. his daughters never do wrong in his eyes and I finally said something about it last night well needless to say he didnt like what I had to say.