My Sister’s husband is sleeping with me – 14 year old girl cried out

My name is, (Name with held) I am 16 years old and my sister’s husband is currently sleeping with me. They have three children. We have been kissing and romancing before we started to sleeping together. When my aunt and her husband are together, we act as if nothing is going on, one can hardly suspects that something is going on between us. Unfortunately, I’m now falling in love with him. I know he will never leave my aunt because he is like the bread-winner of the family and owns the house we live in. I love my aunt and I’m grateful to her for letting me live with them. Should I end this affair? If I do, should I tell my aunt the type of man she has been marrying?