If not already, become a responsibly armed American. If not already enrolled, take self defense courses. In addition, go through all the legal steps available, report the stalker to the police, get a protection order, vary your routine, start commuting with another responsibly armed American. In some states, that last email text in combination with the other texts, social media posts, would be enough for an arrest for stalking.
If you don’t already have your home set up in a secure manner, go through the steps to fortify your home, including an alarm system if you can afford it. If not, there are several options for an alarm type system that don’t cost as much as company maintained alarms. Those are most of the legal options I can think of with only 1.5 cups of coffee in me. Options outside of one’s legal recourse are up to each individual and their own conscious. Edit to add, get one of those security noise makers with four legs like mentioned in the other discussion if you don’t already have one.