Mother-in-law

Where to start....
My husband and I met on match.com. We were married a short 9 months later. He gave my daughter a ring first and said he wanted to take care of us forever. I little after we were married for a year we had a beautiful baby boy.
My MIL was always over involved in our lives. She doesn't have good finances and my husband was always helping her out. She doesnt have laundry facilities and would spend a couple days a week at the house doing her laundry. She would rearrange furniture, pictures, program our DVR, and even organize my underwear drawer.
After our son was born, my husband insisted she watch our son. Six months ago, just before our son's second birthday, while watching him, she had him around our horses, even though we had told her numerous times not to. She told him to sit on the step, because one yr olds listen, and the worst happened. What, we're still not really sure, but when got home, I thought my baby was dead. We life flighted to Childrens Hospital and a week later my sweet baby finally woke up with no long term damage.
After that, I could no longer bite my tongue about all the little things that we driving me crazy. We, my husband and I share all passwords on emails and phones. I checked his one day and there was an email from the MIL, telling my husband that I have mental disorders and that his x girlfriend, who she calls no personality, would have been a lot better. He replies, agreeing with her. I was mad to say the least. He told me he didn't mean it he was just trying to make her happy. I forgave him and put the baby in daycare. Christmas came and we spent Christmas Eve and Christmas with her. We were not social but tolerated each other. Then...two weeks later it was her birthday. In the past, she has always asked for an alone date with her son for her birthday. I told him there would not be any solo dates anymore but we all could happily celebrate her birthday together. She fired back with an email to him, but addressed to me, where she told me I was a fat f...ing C......that she hated loathed and disposed me, we she thought was funny because she meant despise but wanted me disposed of too. My husband said he was sorry and that he defended me, but I guess that only meant that he stopped speaking to her for a few days. But....life went on, no more mean emails. Then this past weekend he was working and walked away from the computer when I saw the screen. He opened up a new email account where she was continuing to write horrible things about me. I checked the history of the computer and he was doing searches for the x the MIL thought he should have married. I was MAD!
I told him I wanted a divorce; he said lets go to marriage counseling one more time, as we've been going on and off for 3 yrs. So...2 days ago I meet him for counseling and...he brought his mother. The counselor asked me what I was thinking and I just laughed that she was now attending our marriage counseling. I said that I didn't mind her saying bad things about me, but that I wanted my husband to defend me. He claimed he does. In which case I questioned that because if he did she would stop. He said she wouldn't and I asked him why he would want a person like that in our lives. He said nothing. I again asked for a divorce. The counselor suggested a separation. That is what he wanted to do, I agreed but didn't thunk it would help as we are already apart a lot because of his work.
After the counseling I asked him why he brought her. I said that when I saw her, I was hoping it was so he could show mw he was defending me. He replied, that we are now separated and he does have to talk to me nor does he want to. The MIL posted her victory on facebook that night, her 30+ yrs paid off, she won and he will always be hers.
I filed for divorce yesterday. Sigh!