i would take it really slowly and just get to know each other again. one thing i absolutely would not do is have him invest in your business. you need to know you can trust him after he cut you out of his life, and i don't think a financial entanglement is a good idea at all. keep your relationship and your finances separate because if the relationship goes south then you won't be tied to him financially. if he wants to give you a financial gift (not a loan) that is fine but no strings.