I think a big part of it, and correct me if I am wrong, might be that you will lose a certain aspect of your identity. Your identity includes where you see yourself in a few years, and this is very different from the “ideal” situation you would like be in.

I am the exact same way as you in that I fear commitment. It scares me because part of me thinks I will regret it and will have no way out. I think when you have someone so great, it’s also equally as scary. My advice, and this is coming from someone who struggles with commitment and with making decisions, try to figure out if you are afraid to not live up to expectations as a step-mom or if you feel you will lose your entire identity and be the “wife of a man with a past” or if maybe you haven’t found something to really ground you in who you are as a person. Of course, all of these are valid, but you have to come to terms with yourself, and really be open to being vulnerable and honest with yourself. I think once you stop worrying about what everyone will see it as, the real answer will come from within. That is easier said than done, but whatever decision you make, see it as an addition to your life, not a defining factor or anything bigger than who you are as a person. Instead of being the wife of a man with a past, you could be Jesslou who married into a great family. or Jesslou who loves chess and kayaking and has an awesome supportive husband. Don’t let your identity be masked by this big event in your life. Marriage is huge for everyone, especially us commitment phobes, but once you let the muddy water settle, you will be able to see clearly and find yourself.