What hyperlexian said. Especially the part about concern over the potential stalking (or worse).
By no means am I recommending that you contact him, or how to handle things at all. However, one (possible, not guaranteed) way to reduce the risk of post-relationship stalking/craziness is to explain your reasons, exactly as you did here. Honest, simple, brief. "I was looking for companionship, not sex. You are looking for sex, not companionship. We have conflicting, incompatible needs, which makes this is totally wrong for me. I think you have many good qualities and I enjoyed the time we spent together. Nonetheless, I have to break it off now, and ask you to please not contact me again. I truly wish you the very best." The end.
Again, no guarantees. But I have dated a few loose cannons with checkered pasts, and ended contact in this manner. Respectful, compassionate, humane enough to give them a reason, but firm that they were not to contact me again. They all respected my wishes and left me alone (and in one case, I was surprised that he was able to control it).
One other comment.
Quote:
No one else would want a 50 year old unemployed ugly single virgin. I basically have to take the bottom feeders if I want anyone at all.
No one has to take the bottom feeders - you only
think you do, because you've defined yourself in such negative terms. Think of all the positive things you bring to the table, and stay focused on those. Maybe make a list, and keep adding to it. For example, you're 50 - not 85. You are creative - not a brain-dead zombie staring at TV all day. Your lack of need/want for sex may come as a huge relief to an older gentleman whose "equipment" doesn't work so well anymore, or whose libido has waned. Just be careful not to let a low self-image lead you into risky situations.
I think this is great advice. I really like the quote of what to tell him for him to get the message if he continues to contact you. It's staight-forward but not insulting or offensive. I wish I was able to express myself that well.