You said he "skipped" last month, but you're not sure because of taking Peaches to the vet. Is there something about the middle of the month that is significant to him? Do you think maybe daughter did mention that she contacted you? Just thinking "aloud" here to find his pattern. I don't think it was just a coincidence that you caught him heading in the direction of your apartment.
I'm glad you have the support of your co-workers and all of these precautions in place. And I'm glad you are going to talk to the police about your options. Do you have anyone in your apartment building that you can go to for help, like you have at work? I think you need to get a neighbor or two on your side to keep an eye out for him and/or to call should you find him in the parking lot or in your building. This business about wearing down people concerns me. It may be beneficial at work as a facilitator, but I see how he could easily up the ante and use these techniques against you because he perceives you to be antagonistic by not talking to him. It sucks that you have to deal with this. Please be very aware of your surroundings at all times.
Is there a self defense class in your area you can take? Some tips I learned from going to college in a rough neighborhood...hold your car keys with each key between each of your fingers and make a fist. Do this when going to and from the car. If you need to punch, you have some extra little weapons in that fist. Always look into the back seat of the car before you unlock the door to make sure no one is hiding in there. And if you're walking and feel someone is following you, cross the street and keep objects (preferably parked car between you and the other person. If you feel the need, drop and roll under one of the parked cars and scream your head off. It causes a commotion and the "assailant" won't take the time to pull you out from under the car.
I just don't trust his mental state and the fact that he so thoroughly sees you as HIS possession. Better safe and feeling silly that sorry.
Take good care and hugs to you and Peaches.