grown step kids

I fully understood what I was getting into when I married my now husband who had 2 children from a previous marriage.  I did the best I could, financially supporting their school, vehicles and pretty much everything else since their mother is pretty much broke all the time.  I've lived with them for 7 years.  They are now 18 and 21.  My husband and I now have. 2.5 year old and one on the way.  We just returned home from a week long vacation without his older sons and had a great time.  It was relaxing and fun.  The older boys were of course invited and planned to come but changed plans when they decided to stay behind and work.  Over the past 7 years we have all gotten along very well.  We had vacations, I've organized birthdays and events and always helped with school, resume writing, tuition whatever I could.  Lately, I am started to feel like I really want them to move out.  Tonight when we returned from vacation the eldest, decided to rearrange the kitchen and change all the pictures around.  He even took some down of my newphew, yes they weren't in frames, but should that matter?  This isn't the first time he had rearranged furniture to his liking or took down our sons art work on the fridge. It's starting to really annoy me.  It's not so much moving the bread box from here to there but it's this idea that he doesn't respect that this is really not his place to be moving things around.  I have brought this up to his father several times and with an infant way in just 10 weeks I really to get to a place where I'm not daycaring for grown kids.  He is ready to get a divorce because he feels like I'm asking him to cut ties. He is being overly dramatic and that's not what I am asking.  I just need peace and stability in my home.  It drives me crazy, there will be garabage rotting in the kitchen and recycables overflowing from the but he feels the need to move my mantle pictures and arrange things how he likes them?  It's driving me insane.  He also walks into my room every morning to grab socks and underwear from his dads drawere because his room is a mess and he never does laundry.  Am I such a bitch for not wanting my grown stepson in my room every morning?? My husband is not getting it and I don't know what to do.  He says he will talk to him. It we have been through this about a dozen times and nothing changes!  Any advice??? I don't think I'm being unreasonable.  When is enough enough???