Dia, you are in a strong place. Thats why I suggested you make him aware of those boundaries sooner rather than later. If he breaks up with her telling her that they can "still be friends", and you later say no. He will feel a little manipulated. Since he made a clear statement that he wants to remain friends, I think it is best you let him know you can't live with that and explain your very valid reasons why. Otherwise, he will say "Well why didn't you let me know earlier?"
You are doing a great job and an inspiration to everyone here.
