I would have a quiet word with your neighbour NOW.
Ask her to keep the matter between you and her.
Like others, I cannot feel that she is likely to be romantically interested in your husband, but you never know.
I find the prospect that a woman of 44 feels harrassed or stalked by a man your husband's age far more worrying. She may well be hesitiating to approach you or go to the police, but be worrying about this situation.
Looking back, I would have appreciated the wife of a man behaving like this to me, to have let me know that she knew what her husband was up to, did not approve, and was trying to stop him making a nusiance of himself.