If she suspects it, and if she fears it and will hate you for it, would she really make a joke about it? Few things must be harder on homophobic parents than to learn about their homosexuality of their child. Not stuff to joke about.

Now I don't know your mother. But that would be weird to me. Then again, that might be typical behavior for her.

Now maybe she said it out of anger and frustration, so what Bill3 says; what were her feelings?