DnJ and Gerda have given you good advice. I would also suggest that you join a group. You love to take photos and then are great. Is there a photography group in your area? Think about the things that you love to do during your down time, minus loving on your kitties.
Talk to your son that is still living in the area. Share your fears with him and I would definitely think about getting the app that Andrew mentioned or one like it.
It's time for you to dip your toe in the unknown and reach out just a wee bit. I get it that you are hesitant to reach out, but in order to have the community wrap its arms around you, you have to reach out a bit.
Fear has a way of keeping us frozen. Don't allow fear to keep you from enjoying your life. Your kitties love you to bits, but you also need human interactions. Here's a thought...have you thought about joining a cat rescue group? You have such a huge heart and feed the strays in your area, this might be one way to give back for all the love your precious babies give you.
Just some food for thought. If you want to bounce ideas off me, you know where to find me.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
