Can't live with or without U

My Sag guy was very clear from begining that a "GOOD TIME" was only what he was looking at in our relationship,but over a period of time he developed feelings for me,proposed me and wants to marry me,we both love each other very much but knowing his womanising past its difficult for me to c him as a husband material.
Being a gemini and a completely independant woman for that i find it difficult to forget his past or trust my life/future in his hands. I dunno how to handle this coz its difficult for me to let him go away from my life becoz i feel complete with him....
how do we handle this " can't live with or without you" situation.....—?