I’m very sorry this situation is so painful for you. However, it does look to me like you are not taking “no” for an answer. She may not have given you a direct “no,” but she has definitely signaled that she isn’t interested in a relationship with you and may even be fearful of getting closer.
The other possibility is that you are indeed in some kind of medical/psychological trouble. You are at an age where physical changes can result in what looks like paranoia and perseveration. I strongly urge you to stop focusing on this woman, and instead start focusing on your own health. Make an appointment with your physician for a complete medical exam. Share what you told me here. Ask the same questions.
If you are medically fine, then please do yourself the great service of seeing a mental health counselor. A “no” of any kind is a “no”. If you can’t move past that and think you will sink into a depression, then you need and deserve the support and guidance of a counselor. Romantic disappointments hurt. Often people who have been rejected find it very difficult to accept. You are not alone in that. A counselor can help you grieve this relationship and gather the strength and optimism to search for love with someone who can return it.
You are 62. You may have decades of life to go. I think you deserve to take care of yourself and move on so that you can find someone who can love you and cherish you for years to come.
I wish you well.