Hi, Shamus! Wow, talk about roller coaster! Glad things are headed in the right direction. The important thing is we learn from our pain. I know way too many who keep getting back in to the same bad relationship dynamic over and over and over... I read an intesting study on love a couple of days ago...
The good news is small ceramic heaters are low cost (under $30 -- one of the best investments ever) and should be more than enough for a bathroom. The question is whether your house wiring can handle the heater amperage requirements. Dad might know if your bath outlets can handle 10 or 12 amps.
Can a small portable heater be used in your bathroom? I don't know how people used to use outhouses in the winter, but I do understand "when you gotta go, you gotta go!"