Wrong for whom, or what reason? I mean, there’s no law saying that you have to observe Mothers' Day in any way whatsoever.
If you are still chasing approval or affection from the defective creature who birthed you, you more than likely know on some level that’s not going to happen, and this has created a bitter need to hurt the person who hurts you by dismissing and rejecting your attempts to please them.
If you want a reaction or a conflict in lieu of any softer form of acknowledgement, yes, you will likely get a rise by sending a rude card. But, stop and ask yourself what you hope to accomplish in the long run with this gesture.
I suspect this impulse is coming from your wounded inner child and I suspect that grown-up you knows such an impulse is foolish and destructive, even if it gives you some temporary satisfaction to ‘put her in her place’ or 'get her goat'.
If someone has dismissed and rejected your attempts at kindness and generosity, you are not obligated to gift them or acknowledge them in any way any more. You can still send a card or give that person a call to say hello, but it is best for your own healing and for your sweet, hurt inner child, to keep contact with that person as brief and impersonal as possible, given what you now know about your mother. You don't have to let other people's ill treatment of you make you into a person who is mean and deliberately cruel. If you become a monster too, then the monster wins.
On this Mother’s Day, nurture and love your inner child with something special for yourself, be it brunch with friends, time with a child, animal, garden, or some other young life you can give ‘mothering’ energy to, time with a person who gives you nurturing and ‘mothering’ energy, a quiet walk in nature, a day with a good book and delicious warm tea, or some other healing, healthy activity for yourself. Just for you. Give yourself the mothering you wish you had gotten, and the gratitude and kindness you wish you had received.
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