I'm not really one to be giving advice (MS1), but if you don't do family practice, what are you going to do with that year? It seems to me that if you do family practice and then reenter the match, you will look better because the psych programs will know they are getting someone with a year of medicine under their belt.
Somebody on this board has to know someone that's been in your situation, so hopefully they will chime in with advice.
Family practice because there are spots open or family practice because you like that field second best? I ask because the people I have known in FP internships worked their tails off; it sounds a lot like 3rd year take two, with more pressure. Maybe some programs are kinder and gentler- the programs I have known people in were academic, and maybe FP departments feel like they have to prove that they're tougher and more dedicated when they are competing with "the experts" in the specialized fields- but if money doesn't make an internship mandatory for you, I'd advise thinking long and hard before signing up for an FP internship.