He doesn’t know I’m older

My boyfriend is five years younger than me, but he doesn’t know it. He is physically much bigger than I am and so maybe he just assumes that he is older. I also feel that he is about to propose marriage to me.

I don’t know how he will react when he finds out that I’m older than he is, so I’m kind of confused about what to do. I don’t know if I should tell him now or later when we are already married and have a child I love him very much and I don’t want to lose him. I cannot live without him and I cannot stand to see him with another woman. He is very mature and so loving to me. Please advise.  {Kenzie}