How do you deal with a controlling, interfering mother-in-law?

My MIL has caused so much stress in my life over the past 3 years. I am to the point that I cannot even look at the woman. I have such anymosity toward her, and I am not sure if what I am feeling is me just being petty & just not letting go of things, or if I truly have a gripe that needs to be addressed. My MIL comes to our home, looks through our mail, reads & searches through anything that is laying out in the open - I feel as though I have to "hide" everything before she comes over to our house. My husband & I have a lake home, and she insisted on having a key made for her to be able to use it when she wants to - my husband & I have had many discussions about this, as well as it causing a strain on our relationship. She invites all of her family for an entire week to come and stay at our lake home, without even asking us, but in fact tells me "It's going to happen, so you need to just deal with it!" She never talks to me this way in front of my husband, so my husband questions my interpretation of conversations with my MIL. My MIL constantly puts down her husband, who is one of the greatest men I will ever know in my life - he is very giving, happy, outgoing, supportive, loving, and just plain kind to everyone. Again, she never does this in front of others. She refuses to cook for him, clean for him, do laundry for him - "I've done it for over 40 years, I'm tired of doing it!" is her remark. She has said this in front of my husband & he totally laid into her. She is in bed every night by 7:00 & constantly talks about how tired she is. I don't call her anymore, because I am either intruding on her sleep time, or her computer time, and get chewed out for either one, so I stopped trying to call her. She never calls our house. She will rarely do anything for us if we ask her to, but yet she feels as though we can do everything for her. I had surgery last fall & needed some help with our daughter, as my husband was out of state on a hunting trip. I had made all the arrangements at my daughter's school as to what was going on, and low & behold, my MIL went & screwed it all up - she took it upon herself to tell the school something different, and they did not notify myself or my husband. Needless to say, the school staff was told, under no uncertain terms, that she, or anyone for that matter, is to dictate what goes on with our daughter - unless they hear it from my husband or myself, no one is to change anything for our daughter. My husband also laid into her for that once he found out what had happened. I had bi-lateral carpal tunnel surgery(outpatient) - I drove myself to and from my surgery, just to avoid having my MIL around. She came to our house after she got off work, and then left once I was settled in & my daughter was taken care of - which was very kind of her & I did appreciate that very much. She told me to let her know if she could do any more, to let her know. Well, I did ask her the following day if she could stop by to help me with a few things, and the response I got was, "I suppose, if I have to." I told her to not come, because I didn't want to interfere with her plans, so she didn't come over, which was fine. For my birthday, my husband got me this really nice lounging chair for outdoors, and guess who the first person was to sit in it - my MIL - I didn't have it out of the box & she had her behind in my chair. She makes comments to me like, "Well, you know more about what is going on in the family than I do", or "Well, you don't know so and so like I do." I simply cannot win with this woman. She told me once that before I came into her son's life, she used to see him & his daughter all the time. We live in the same town, only 10 minutes apart, is it that hard to see each other??? Every time we all go out for a meal, she makes a complete fool out of herself by complaining to the staff that something is not right with our order - it is downright embarring. I am to the point where I can't even look at her. I have prayed & tried everything to get over these feelings that I have toward her, but have not had any resolve. I normally don't have a problem telling people exactly what I think or feel, but I don't want to cause hard feelings with my husband either - it is his mother, and he does love her, and I don't want him to start to resent me for not being able to be around his mother. Let me know if you all think I need to just let go of it all, or if there is another civil, tactful way of dealing with this touchy situation.