Faces the possibility of a double mastectomy she revealed on TV.
The singer, 33, who also has a 30% chance of ovarian cancer, faces the possibility of a double mastectomy and having her ovaries removed.
Heaton, who was diagnosed four months ago with the mutated gene, said there was a 50% chance of her daughter, who was born in January, inheriting the gene.
She told ITV1 show Lorraine: "It's really difficult to say how you feel when you get told something like that because when you look at your husband and he's getting clearly upset, and then you look at your little baby who is laughing and giggling and she's not aware of anything, you just feel things crumbling around you.
"If I go, will he find somebody else? And I know it's an awful thing to think, but the last thing that you want to do is have your little baby without a mum.
"So I almost give my husband permission to find somebody else if anything ever happens to me because I'd want her to have a mum."
Michelle is married to Irish businessman Hugh Hanley She said she felt "guilt" that her daughter Faith had a 50% chance of having the gene.
"She now has a 50% chance of inheriting the gene from me, so I believe when she's 18 she will be legal to be genetically tested," Heaton said.
She told the show, in a part pre-recorded and part-live interview: "I think what's difficult is timing it right.
"The double mastectomy not so much because obviously that's not going to affect me having children and hormonally.
"But getting my ovaries removed is going to onset menopause and I won't be allowed to have children anymore.
"I kind of feel lucky that I've found out now rather than pre-Faith, because I think had I found out this information before having Faith, maybe the pressure would have been too great to conceive as quickly as I had have done.
"Obviously we don't know, but I'm absolutely fortunate that I've got one gorgeous child, and if that's the only one that I have then I'm fortunate, but of course I'd love more."