I am sorry you experienced such pain. I have a personal belief that sometimes when we hand-craft an object for an intended recipient, that is NOT always the person the divine spirit intends it for. I do believe that things find their way to the right person at the right time. I know you and your sister made that quilt for your mom and that her lack of gratitude hurt, but you said yourself the memories of making that quilt are the true treasure for you. Focus on those happy memories; the moments shared between sisters laughing and creating beauty. I believe that your quilt is happily residing with someone who truly loves it - and however hurtful her act, your mom played an important part in getting that quilt to its rightful recipient. (And no, I am not justifying her callous behavior.) Let go of the hurt and focus on the memories instead.
I can give you a for-instance of this very thing. For many, many years now, I have wanted a decorative broom to hang near my front doorway as a symbol to remind me to sweep negative things out of my home and keep my home and hearth spiritually clean. I never did find just the right thing despite over 15 years of searching shops etc. A girlfriend of mine was at a friend's house and that friend was getting rid of stuff in her garage. My friend spied a broom among the stuff and asked about it. Turns out the broom was a wedding gift to a Catholic couple who reviled it as an evil object and a symbol of evil things. They hated the broom from the get-go. Now the broom resides in my home, where I see it every day and it reminds me to sweep negativity from my heart and home and fill it with love instead. It is an integral part of my home and I am happy every time I walk into my home and see it. Just picture the person who gave the original gift and how bothered they must be that the gift they chose is never on display in the couple's home. In fact, that person may even know it was cast off and be feeling hurt. If only they knew how much I cherish their gift!!!
Perhaps it is a goofy way to think, but that is how I choose to see it.
PS Sorry for the novel. I guess your post touched a nerve for me. ;)