Fiancés mom overbearing with new baby !! 😫

So my fiancé and I stayed overnight last night at his parents place for the first time since having baby, he is 2 weeks old. Right away when we first got there his mom asked for the baby, which I had no problem with it! But she would not give him up after that!!! It was honestly a nightmare! He was starting to fuss because he was hungry (he is a breastfeed baby) and she had him suck on her arm and said babies can’t be content all the time when I had said he was hungry. When I finally did get him back to breastfeed she kept checking in to see if I was done, which I was and she grabbed him and did his burping. She held him for a few more hours until he was hungry again, crying at this point because she let him grunt and eat his fingers for awhile before handing him over. As I was going to switch breasts, she comes and grabs him from me!! 😡 he wasn’t done eating and my fiancé had asked her to give him to momma , meaning me and she said it can’t be about mom all the time! She asked to bring him to bed with her and I said no because he has to eat at least every 3 hours yet, she stayed up with him on the couch until 12;30AM when finally I had enough and went to grab him and took him to bed with me. This morning at 7am she comes down and grabs him again until I left. I’m seriously feeling overwhelmed and like I never want to go back!! To top it off when I was feeding him he was looking at me and she said he’s probably thinking who is this lady (meaning me!)!

Beyond annoyed. How do I go about setting boundaries without seeming rude?!