Re: Did you remain friends with your ex?
My first ex of 9 years wanted to remain lifelong friends and still have a child after our divorce. No thank you...especially after learning about his cheating and the way he treated me during our short marriage (just flipped personalities after years of dating).
I would rather you explain to your kids that you and this guy will not see each other and the older they are then you can go into details. It's nice to have a father figure, BUT this person would just be hindering you from moving on to finding someone great who can really be a husband and father figure to your children.
Plus, I don't believe in ex's being friends. When I met my current husband, I did not know until later that he had remained friends with his ex of 7 years and friends for 3 years. All of his relationships, I learned, did not work out following their break up because each time he found a new woman, this "friend" (his ex of 7 years) would interfere with each of his relationships, so they could not flourish and grow. When my husband and I became more than friends in the time period of those 3 years that I knew him, then I learned that she had went to the point of expressing suicidal ideation and I went with my husband to support him because he felt so guilty moving on in his life as his friend was always having a regular crisis. Afterward, she stayed away because another mutual family member is soon to be a social worker as well, helped and supported this woman and then for months she began to stay away, until she learned of our marriage and first pregnancy together.
So I do not think it's healthy for both you and your children to exposed to someone who could potentially damage you and your children's growth into something better.