It is not whining to reflect on something that is a part of all of us. We are supposed to learn from our mothers how to mother ourselves. But you had that taken away from you, twice now! You had to learn how to mother yourself from a broken system, and I imagine now you still struggle with figuring out how to best take care of yourself, or how to best decide which things are good for you, or how to make decisions and follow through with them and the consequences they may carry etc...
The support system was not there for you, and it's a loss that is absolutely acceptable to reflect upon. How you feel about her, probably should be mixed after what you said, that she may have allowed abuse, and there are many answers which you still don't have etc...
Children do look to their parents for the answers to things; obviously the things you were looking to answer were probably things that no child should even have to ask in the first place.
Perhaps while she was alive, even without her being in your life, you might have felt like somehow you still had a "mother", even if she was not maternal in her instincts... she still physically was alive. Now that she has passed, can you say that you have a mother any more?
Other people whose mothers have passed may be able to look back and still talk as if they had a mom, and talk about the good memories, and all the things they miss; but I imagine the things you miss are quite deep, the opportunities that have gone by, the basic needs that were never met, the love that took so long to even find etc...
What Sadeyes said may have hit the nail on the head too, that perhaps you are missing the idea of the person and what could have been, more than anything else. As you said, you have mixed feelings. You probably wanted her to be so much more for you... and that opportunity was taken away in her death. Another robbing from your life... another abandonment, only more permanent.
But, again, a mother's role is truly to teach us how to mother ourselves, and how to take care of ourselves; so if you miss her, as the mother, and as the person; memorialise her in a nice way, by taking on a task that you probably should be doing to take care of yourself, and work on it, and get good at it. Become comfortable with it, and love it. Nurture yourself a bit, that would be the best way perhaps to come to terms with such a loss, and to begin healing at least in a little way. Just a thought.
