Single mom a turn-off? God no, that is not a turn-off at all, at least not to me or any real man, and real men are all you want anyways.
The way a woman behaves as a mother is extremely telling about her character – probably more so than anything else, so to me there is a lot to gain about the woman you have by seeing her as a mother.
A single mom is just as desirable and in some ways more so than a woman without kids who wants them, at least for men at a certain age who have kids and are not planning on starting another 18-year stint.
In some ways, I have always found the role of a step-mom or a step-dad to be extremely attractive. I have an uncle who essentially stepped in as a dad and became such a big piece of the kids lives the son even ended having him as his best man in his wedding. He is all of their best friend and primary male role model and a damn good one too.
A good Dom? Don’t look at it like that. Find a “good man”. Before you get too deep into the relationship, if being submissive is a critical part of who you are, you need to share this with him and see if he will accept it, run with it, and so on, but the “Good Dom” thing is just a romance novel version of a person. It is a character, not a real person, so just ditch that concept and you will be better off for it.
Find somebody who truly loves you and laughs when you fart, kisses you with morning breath, listens when you talk and doesn’t play with his phone, holds you when you cry, senses when you are stressed, and defines himself through making you happy. I am sure if you ask him to yank your hair and that you like to have structure in your life like tasks and punishment, he will gladly fall into this role. If he doesn’t love you like the examples above, then maybe he won’t. D/s is not for everyone but an open mind will help him understand that it is not about being rough and degrading in bed, but about about being closer and vulnerable to one another, which is a beautiful thing.