MY DAD IS THE BIOLOGICAL FATHER OF MY THREE KIDS

Dear sisters, I’ve been having an affair with my father since I was 15. I got pregnant in the process and that was when my mum found out. She threatened to disown me so I had to come clean that the pregnancy was my father. The shock of this got my mother always thinking because she had no one to talk to, she fell sick and eventually died.
My father and I continued our relationship despite knowing it was wrong because we were so much into each other. After 20 years of this amorous affair with my father, I finally got married and moved in with my husband. Though married, my father and I are still together.
My father always takes me on vacation but my husband never complains because he sees nothing wrong with it. I’m 35 now, I have 3 beautiful kids and they are all my father’s but nobody has ever suspected because I look like him. For some time now I’ve been feeling bad about the whole situation.
I want to tell my husband but I don’t know how to go about it.
Sisters, please help me.