I would simply insist if any member of the family does realise that your Golden wedding is coming up, that neither of you want a celebration and that you had intended to travel instead.
Travel being out of the question, you are postponing the special holiday until is safe to take it.
It is hard to insist on no celebration, but it can be done.
Presumably, your adult children are all reasonably aware that your marriage has never been perfect and is not really a matter for a celebration.
If not, now might be the time to say something along the lines of, "No, we are not going to celebrate this or any other anniversary, as quite honestly your father and I have never really got on for reasons I don't intend to discuss. We chose many years ago now to stay together, but we do not feel it is a matter for celebration."