MIL is becoming increasingly controlling after fiancé and I move in together

For context my (f24) fiancé and I (m24) have you been together for eight years now. We met in high school and are a traditional high school sweetheart story. As you can imagine being together for eight years, we are very close with both of our families as a couple and have received so much support in our engagement and are moving together as a couple. Last year we moved into our first apartment together. We still live close to both of our parents and still visit and spend time with them. Recently within us moving out things have started to change with MIL.

There’s a lot of little things in between that add up, but I’m gonna focus on of the bigger issues/occurrences that are really weighing on me.

The first occurrence is that MIL stopped by one day unannounced. Which is not a problem family is always welcome and we enjoy company. It just happened that I had prior engagements so I stayed for a little but ended up having to say my goodbyes so I left my fiancé and his mother alone and did my thing. when I came home later that day, MIL was gone, but my fiancé told me that something really strange happen that he did not feel comfortable with. He says that the second that I closed the door to leave MIL pulled out paperwork from her purse and casually asked him to sign. This paperwork ended up being a power of attorney health directive. In short asking him to sign away all medical rights to her in cases of emergency. This would trump marital rights to health directive as she would have the power of attorney. Obviously, we told her no, but made it clear that it was strange that she waited until I had left before bringing this out instead of asking both of us as a couple what we thought of this idea, she doesn’t agree that it’s a strange thing to do and doesn’t understand why we have a problem with it.

The second and current issue. My fiancé and I have been looking to purchase a home for when our lease is up at our current apartment. We have been looking and both of our families have been aware and have been helping us in our search. We finally found a place and put in a contract. Excited was an understatement. It was everything we wanted and we got a really great deal and we are still very very close to both of our families equally as close I would say. When we broke the news to MIL that we were under contract, she could not hide her reaction that she was Upset or disappointed. I’m not even sure, but she was quiet and could barely look us in the eye and change the subject shortly after we told her. this was pretty crushing for my fiancé, and I, as we were really excited, and everyone else had good reactions and excited reactions for us prior. We decided to bring her to the house to do a walk-through to maybe change her mind. When she was in the house, she fell in love with it, and was showing that excitement that we were missing from her. The next day she casually sends my fiancé a text “wouldn’t it be nice if we were neighbors lol “turns out she had already gone to the neighborhood with her realtor to look at a home down the street. She has been looking for a home herself, and because it is new construction there are good deals and incentives they are offering, but the same street may be a little too close for our comfort. My fiancé mentioned looking at one of the homes on the other side of the neighborhood instead of the same street and her answer was well if I get the one on your same street then what’s the big deal it’s turned into tears hanging up calls in the middle of conversations and “if you don’t want me close then I’ll just stay out of your lives from now on “

I suppose I’m getting to a point where I’m wondering if I’m being too protective and blowing things out of proportion. I know she’s doing things out of love for her son but this doesn’t feel right.

How do we get her to see our side?