What to do about my mother in law! warning LONG?

Okay here's the short of the story. My husband and I have been married 3 years together for 7. We'll start w/ our wedding we got engaged and started planning a wedding for the following summer which was a little over a year away. For starters my SIL who at the time we worked at the same place went around as soon as we got engaged telling everybody we didn't belong together we were never going to last. Out of the blue she had just called me to go shopping the night before we got engaged! So i went home in tears DH called his sister flipped out on her told her he didnt care if she came to the wedding but the shut her mouth. Well he wanted his sisters in the wedding I agreed but it was like pulling teeth to get them to go be fitted for dresses anything. Our wedding colors were blue and silver I had my MOH in silver & Best man in silver and planned on having our dad's tux's match whatever color our mothers wore I asked that they please not wear silver or the same ligth color blue the bridesmaids were. Well my MIL went out and bought a dress the exact silver color of my MOH so my FIL & our best man would of been wearing the same thing so I ended up having my dad & FIL in all black. The whole year we planned our wedding she never asked how things were going nothing she talked about she can't wait til her daughter gets married (who wasn't engaged) and planning things for it while we sat there. After we got married we got pregnant the month after w/ our son everything was great until our son was born I had to have a c-section so we wanted to keep it a suprise still for everybody so we only told our parents the day he was going to be born so they could both be off to come down and see there first grandchild well my parents came down w/ us at 5am and waited in the waiting room until visiting hours at 12 my inlaws however showed up around 12:45 my MIL made nasty comments the whole time about how I was holding my son and then left at 1 to go to work. Since I had a c-section we didn't go anywhere for weeks after we got home everybody came out to see us my mom brought us food out daily and called to see how we were and if we needed anything. My MIL didn't call didn't stop out (she lives 5min. away) when our son was 4 weeks old my SIL's came out to visit and my MIL was suppose to come w/ them DH was excited his mom was coming to visit cause she only saw him for 10min. the day he was born. Well his mom didn't show up but his sisters came in yelling at us saying we needed to take Wyatt down there and let there mom watch him shes home crying blah blah blah. DH called her and asked Y didn't you come up I thought you were coming? she said oh I decided I wanted to clean my carpets today! On mothers day (my 1st) we went down to visit and my husband his sisters and parents all went out to eat I wasn't invited. But I thought id be nice and I told her I woudl come back down after they got home from eating so she could see Wyatt she said oh ok that would be nice so I drive back down only to find my MIL decided to go shopping w/ her daughters! My son is now 2 and my in laws have saw him maybe 12 times in 2 years we invite them up to visit they dont come. She didn't even come to his 2nd birthday party & I booked it 2mths in advance and called her to tell her when it was so she had time to get off work. What annoys me is she doesn't seem to want anything to do with us or w/ my son until there is a family event like a wedding then all of the sudden she is "super grandma" and wants to walk wyatt around and will sit and say what he likes and doesn't like and she has no idea what shes talking about my son LOVES spongebob she told people he doesn't like him. And will always make jabs like she isn't use to being around little kids she never gets to see Wyatt. And then everybody looks at us like we aren't letting her see him. She always plays the victim. We are currently expecting our second child due in December and I am already stressing out about how she is going to act this time around. I want my kids to know both sides of the family but at the same time I dont' think its right to them to have to force them onto somebody who only wants to be around them when it is convienant for her. I just feel when its good for her she wants us around when its not we dont even get told about family gatherings unless she wants us there anytime DH talks to her he's always saying oh how come nobody told me we didn't know! I just don't want my kids to be let down by her. Any suggestions? Thanks! And sorry so long!