I can't stand my 2 step kids and i feel horrible about it.

My husband and I have been married since April. I have a 14 year old and he has 8 year old twins. My daughter lives with us full time and sees her dad on weekends. His twins live with their mom and we see them every other weekend. The problem is is that I can't stand the twins. They act like they are 2 instead of almost 9. They are completely helpless. They can't open doors (house or car), they can't get themselves a drink, they can't tie their own shoes. When they go to the bathroom they don't wipe themselves, flush the toilet, or wash their hands. This is disgusting I know, but one of them went to the bathroom and i guess got poop on their hand and wiped it all over the wall and door in the bathroom. When they don't feel like stopping what they are doing to go to the bathroom, they just pee in their pants. The girl is a chronic bed wetter. She pees on couches or beds wherever she falls asleep. I have put my foot down and will not let them spend the night anymore because furniture is being ruined. My daughter spends every weekend with her dad, so when the twins were spending the night they would go into my daughters room at night and completely destroy it. The girl is VERY jealous of me. If she sees her dad hug me or kiss me or hold my hand or even attempt to sit by me on the couch she starts pouting and whining and talking like a baby and calling her dad "dadda" in a little baby voice. She has even made herself throw up when she thinks she is not getting enough attention from her dad. Every 5 min she will walk up to him regardless of what he is doing or who he is talking to, interrupt him, kiss all over his arms, and say in her little baby voice" i love you dadda". When they were spending the night she would even tell me that "she was going to sleep in bed with her daddy" even though she never had before before we met. They always had their own room. Luckily he nipped that in the bud real quick. She tortures her brother when no one is looking then when he gets mad and yells at her or hits her she starts crying and he gets in trouble. We can't take them anywhere. We are basically prisoners in our home when they are there. If we have to take them to the store it's torture. They touch everything, knock stuff over, and grab things off shelves. They will walk out in front of cars without even looking or just simply wander off. I start dreading their visits days before they are to arrive and it puts me in a bad mood. It has gotten to the point that when they are there I don't even come out of my room.