MIL Issues

My husband and I are 34 weeks pregnant and I don't get along with my MIL very well. She wrote me an email prior to getting married and called me a bitch along with a few other choice words. She never apologized and since then things have been tense. We still see them on occasion as they live out of state. They are coming to town this weekend for one of my showers and I told my husband that I'd  spend some one on one time with her to talk things out and see if we can resolve anything. Here is the kicker...we recently bought a house and renovated it and the in laws had never seen the house. Once we told them we were expecting, they went and bought us a surprise. Turns out it's a $3000 piece of art they want hung in the nursery. However, I had already spent lots of money on nursery decorations and what hey bought us doesn't go ANYWHERE in our house. I am a bit stubborn and don't want to hang it just to please them. I had a vision for the nursery and feel that my husband and I need to do what is best for us and not hang it just to make them smile. They didn't ask us about colors or themes prior to purchasing the expensive piece. I feel that it should have been discussed if they wanted to spend that much on a piece of art for the baby. I have to explain to my MIL this weekend why it's not hanging and she takes everything so personally, how do I keep my cool without rolling my eyes and telling her that it's just a not a good fit for our family? I also have to explain that moving forward they need to get a hotel because I don't care to have house guests once the baby arrives. I feel that my husband should be having this talk, but I agreed to take on his mother this weekend and he would talk to his dad. Any advice would be wonderful. I want them involved, but selfishly on my terms. I just need boundaries between us. Things are going to change for all of us and I understand it's an exciting time for them as well. Thanks in advance!!