doublecheck this comment was meant for you and your MSPE with your school's office
at my school, you could challenge instances where there great discrenpecies between grades and evals, it wouldn't be wrong to just *nicely* bring this up to your school's office depending on your school's culture
at my school you could contact the clerkship director, however, it's important that if you do, and that if they are involved in the residency process at all, that you are *extremely* diplomatic, given your MSPE comment you may or may not have this skill
the way to go about it would be to just express surprise at this comment, you didn't see it coming, and you would just like to have more feedback if this is just what the evaluator thought of your performance (the implication being that perhaps this wasn't *exactly* how they wanted to word it.... this could lead to an edit that might soften the language, or it might just teach you something you clearly need to know, because being perceived in a way that one can't connect to one's own performance... is worth addressing) the latter half of that parenthetical statement would be the part you would want to state as your motivation, if you went this route to look into this
those avenues aside, all specialties know that you rotate in other specialties, and would expect you to show interest and do well. as far as having "intense interest" that's fine
usually programs wouldn't know you're applying to more than one specialty unless you tell them, it's somehow gathered from your LORs, you're asked directly, you apply and interview for both programs at the same institution, or they just have a spidey sense
if that happens, I don't know what to tell you
if you're asked if you have any other specialty interests or "your letter notes intense interest in psych" etc:
some specialty interests you can *easily* leverage into "why this other specialty is right for me"
you can say how much you appreciate addressing the psychosocial determinants of health, understanding your patients from an emotional standpoint, the doctor/patient therapeutic alliance and its psychology, and that was what you enjoyed about psychiatry. however, you feel you would be extremely frustrated in not using those skills in managing the "whole patient", diabetes and other chronic illnesses included. you feel that family medicine is right for you for blah blah blah that is specific to FM and not to psych, and that you think you will get plenty of psych-related exposure and use of your strengths in that field in family medicine.
just ideas
best of luck, and ditto what people said above, defensiveness, no matter how much you may have been wronged, will get you NO WHERE in medicine, ever