Am I overreacting?

My SO and I have been dating officially for about 4 months. We were friends for seven years before that. 
At 28 I've been married and divorced twice. I have three children from my previous marriages. 
My first marriage was to a man I had known since elementary school and dated all through high school. He turned into an abusive alcoholic who would cheat on me and later (after our divorce) threatened to kill me and our daughter. We now have a restraining order on him and I never have to deal with him again. 
My second marriage was to a man I dated for six years. We were married for one. I was high pressured by friends and family to marry him when he proposed after I kicked him out of my apartment. He had zero ambition and was a massive hypocrite when it came to morals. He would guilt trip me for not being home to take care of the kids when I worked full time and went to school full time. 
In both instances I filed for divorce. I refuse to stay in a relationship with someone who is less than what I deserve. 
Now to the actual question: my boyfriend mentioned getting married a few weeks ago after we found out I'm pregnant. 
I had an asthma attack and fled the room. 
I'm not really interested in ever getting married again. Baby or not. I refused to live with him as well. I like my new independence (this was the first year I ever lived on my own without a roommate or parent or partner). I like my space. 
I love my boyfriend dearly and he's an AMAZING man. Better than I feel like I deserve sometimes. But honestly I've never pictured myself being with anyone for the rest of my life. I certainly never thought about getting married AGAIN. 
His parents are amazing people, he's a great man - very hard working and takes good care of me when we spend time together. Am I just overreacting? He and I have very good communication and I've already told him I never pictured myself getting married again. When we first started dating I didn't picture him as being the type of man who would ever want to get married. 
EDIT: the reason I never have to deal with the first exhusband is two fold.  The restraining order is permanent and since we divorced he became a sex offender when he raped a minor. He isn't allowed near minors. My daughter, at 8, knows he exists but expresses little interest in him. I don't bash him but the one time she asked why he wasn't around I just told her he wasn't ready to be a dad yet. 
And it has nothing to do with commitment. I'm perfectly content with being his partner in life. I just don't see a need to rush into marriage and living together because our birth control failed! I don't believe in abortion and neither does he and "not being ready for commitment" sounds like a shitty reason to scramble up and suck out our baby.