Came out to my stepdad. Not sure if I should tell my mother?

So, I came out to my stepfather last night. We had been sitting on the porch talking for awhile, and I just felt the time was right. He took it really well, except that he doesn't believe I'm a lesbian because I was married to a man for so many years. He thinks that means that I must be bisexual. I didn't argue with him, but I told him that yes, I'm sure that I'm a lesbian. I told him that I want to tell my mother, but I don't know if she'll take it as well as he did. He offered to tell her for me, but I told him I would rather do it.
Later in the evening I had a few minutes alone with my mom and I told her that my stepdad had a serious conversation and that I had something important to tell her. She told me that I didn't need to tell her what it was. She didn't want to know.
The thing is, I have already told her, years ago when I was 11 or so. She told me at that time to just pray about it & god would "deliver me". We never talked about it again & that was 20 years ago.
So, I'm sure she knew last night what I was about to tell her. I think she's just uncomfortable with it or in denial. Should I try to bring it up to her again or just let it go?