Thank you for bringing your question to Just Answer!
I think it's time for a new boyfriend. Three years is long enough for anyone to know if they want to be married. In the same way that there is no reason for his daughter to get a job, there's no real reason for him to get married--he likes things just as they are.
There are so many red flags in your description of him that rather than work on ways to get him to commit, I would suggest you put that energy into finding someone who will move the moon and stars to be with you. A man with a 20 year old daughter living with (and off) him, and who keeps you at an emotional distance is not a great candidate for marriage. Would you really want to spend the entire rest of your life with a man you had to talk into marrying you?
I know it may feel like you would have wasted the past three years, but with his track record, there's a good chance you could waste several more years just to end up with him lusting after some other women who is out of his league. And yes, that was an insult when he said that.
Frankly, I think you are out of his league as well. He's led you on, still has some attachment to his deceased ex wife, doesn't have the backbone to get his daughter and her lover out of his house....why would you want to marry this guy?
Before you get involved with another man, first read Temptations of the Single Girl. The "temptations" are thinking that we can change a man or his behavior, settling for a man who doesn't want a commitment when we really want marriage at some point, and wasting time with the wrong man because we're afraid to be alone. Here's a link to the book: http://www.amazon.co.uk/Temptations-Single-Girl-Nina-Atwood/dp/1587368986/ref=sr_1_1?s=books&ie=UTF8&qid=1320317488&sr=1-1