Hello Irma, it's a difficult one isn't it, especially as you don't know if your GD receives the gifts you send.
We never sent our GC gifts but cards for their birthdays and at Christmas for about 7 years, we've been estranged for 10 years, and they are our only GC. We always got two cards, sending one and keeping the other for their memory box.
We stopped sending them 3 years ago when we no longer felt the need to do so, so base your decision on how you feel. If continuing to send gifts and cards fills a need, then carry on.
Those of us who are estranged are in a permanent cycle of being damned if we do and damned if we don't. Some EP's continue to reach out with cards for example for years, with no effect. Others like us, never sent our ES anything once we'd been told we were no longer wanted, and that didn't make any difference either.
A memory box left to her in your will, will one day show her that she was loved by you and never forgotten.