Is it normal i dred my fiances daughters coming to our house?

Help! His girls are ages 6 & 3, He is 38 as I am also. His exwife is 31.
The "girls" come over on Friday after he gets off work. When they get here, he instantly puts in a dvd (Hello Kitty or Disney stuff) He works a FT job (40 plus hours) just as I do. But what does he do? He plops on the sofa and sleeps at one time, 5 hours. Meanwhile the little one has to go to the bathroom 20 times. She cant wipe herself and NO ONE can do it but daddy or she screams bloody murder...so she runs bareassed through the house, and the oldest gets bored and starts pasting hello kitty stickers on all the furniture, walls and windows. So when I get home from work I see, a 3 year old in no underwear, diaper or pants, totaly bare assed climbing all over our new living room sofa (unwiped), stickers plastered throughout the house,juice boxes spilt on the floor, and Kraft cheese wrappers, skittles and twix smashed in the rug and all my art paper wrote on with one crayon scribble...Then I see him sleeping on the sofa. I wake him up and he gets mad at me for having an opinion on the situation. --- An argument.
Another scene is going out to dinner. I always feel like we are the Clampetts. Long story short, we've got the 3 year old screaming and hitting me and her dad because we didn't go o DQ like her mommy takes her. Then she starts screaming because her sister got a bigger drink than she did. The oldest who is 6 now, can't sit still and flops around crawls under tables and pouts hideously when she says she is done eating her food and demands dessert. Both of the children whine, fight and hit non stop. Me even.. They hit and throw things at each other and us. He makes un-followed through threats to them. For example (this is EVERY TIME---NOT ONCE has he ever followed throug to idle punishment) "Mary, if you hit Alice again, we are leaving the pool!" he spanks her softy, then he asks Mary the 3 year old for a "sorry", he sweet talks her and we end up staying till 6pm. My fiance is a shopping addict..we went to WALMART of all places, he told his kids to behave inside the store...Im not kidding, the second we walked in, they both through a temper tantrum because we wouldn't let them play the drop claw machine. He says "One more time you ask to play that game we are leavin and no candy for you both!" They acted up even more hideous in the toy isle because he feels he needs to buy them something every time we go shopping...he tells them again if you don't stop we are leaving. Makes his idle threats, now, a 3rd time in wamart and we arent there 25 minutes, Mary hits Alice in the face with her Hello Kitty Coloring book she threw a fit for..and Alice gets blamed for being to close to Mary. Im sick of this. He has asked me time and time again what he is doing wrong, because he does get frustrated with them. He blames thier mom, but I blame both of them. I give him advice when he asks for it (which is usualy when he has had enough of thier shit) and even when he dont. He nor I was raised like the way these kids or many kids now days are are. I have two teenage daughters. 17 and 15. They NEVER acted this way. If my kids acted up when they were that age or even older (which after a few times of consequences they learned). We would leave the store, restaurant, or where ever. Am I TOOO stict and should let things be to avoid argument. Every weekend hiskids come over, him and I argue. He thinks I am being to cranky and need to just bend over backwards and make hello kity pink pancakes, and just not have a voice when it comes to him and his kids destroying the house when I spend every waking minute cleaning when Im not working m fulltime job. But when they leave, he wants my shoulder to cry on because he misses them,...and thats when he says he is sorry for being such a loser asshole parent. Im so lost.