I think a lot of us place too little emphasis on ritual and rites of passage in American culture despite many people needing such things. I know I do, which is why I plan to ritualize my hysto and turn it into an initiative ordeal, to use pagan lingo.
But there's an infinite world of secular rites of passage, too. I've always found the symbolic burning or burying of things to be really cathartic. Throwing a party or making a special food, or heck, a cake with something meaningful written on it, are things I've seen others do for coming out. If an event is warranted, symbols are more important than lots of us give credit for. Maybe your "funeral" could be butterfly-themed, and in the "casket" could be an old shirt and photo of yours that'll get "buried" in a landfill later. Replace eulogies with toasts. And so on.
It doesn't have to be a serious affair, either. It could be affirmative for you, healing for your mother, and fun for everyone involved.