Invading Mother-in-Law... Need advice!?

Heres a lil background....My husband and I have been together for 8 years... 6 of those years have been spent a state away from his Mother... we use to live in the same state but because she is very controlling and very nosey we moved to get some space from her. Things have been wonderful having our own lives, seperate from her. Dont get me wrong, I love her. She just tries to give her input in everything and wants to ever detail about our lives... all the time... She expects us to talk to her everyday, which I don't even talk to my own mother that often. So, 2 years ago I had a son... My mother-in-law literally tries to be his mother. Sounds dramatic but, she totally tries to take over. Everyone who has seen this relationship between her and my son always bring it to my attention, saying how weird it is that they are so close to him and how she tries to take the mother role.I guess I would be able to shut my mouth and just bear it but they are here every other weekend and its driving us crazy. NOW! They bought a house RIGHT down the street from us and my husband and I have had absolutely no rest from visits from them. The house is their vacation home but they are there for a week, almost 2 at a time. Also, NO ONE will come over to our home if they know my mother-in-law is here because no one can stand how nosey and overbearing she is... She is also extremely rude but I think has no self awareness. lol. To top everything off, they bought the EXACT same house as us... and knowing that my husband has been out of work for almost a year, have rubbed everything they are doing to the house in our face. Dont get me wrong. I am not a materialistic person... but its really starting to rub me the wrong way, and I am only human afterall. This is a converstation we had MIL- "We are going to get the 18 inch tile for the house" Me - "yeah, thats the size we got" MIL -" oh, you guys got the 18? Ohhh, then we will be getting the 20" ...MIL "we are going to put the same opening in the wall that you guys have, only we are going to do it with an arch, because it looks better." Anyways, sorry the story is so long, but thought you might want some background. I feel like I am going to burst fromt he seams and explode at her and I really really do not want to do that. I just don't know what to do or say but I have to do something because I feel trapped. Any advice would be much appreciated! Thanks!