I have a two month old son with my boyfriend, and he has become very aggressive with me. I told him that if he didn't change he wouldn't be allowed to see his son anymore. He promised to change and told me to draw up a legal contract stating that if I saw him as an unfit father in the future that I could then take full custody. In other words, he would sign away his rights to his son if he didn't change. He said that this way if he failed to be a good father, and there was a custody battle in court that I could walk out with full custody. How do I go about making a contract like that valid?