I'm sure the vague response is because each situation is unique. Walking down the street arm in arm with your best friend may seem completely harmless to him, while if you did the same with someone else, it might set off triggers. I have good friends that I'm comfortable being much more touchy/feely with than others. I've stopped censoring that for myself, but my problem has never been being too touchy/feely, but the opposite. If your pulling away is causing a disconnect between the two of you, find a middle ground (less than it used to be, but more than your allowing yourself now). It seems like you may be super sensitive about the image you are trying to portray and your shutting down certain things that are just part of who you are. I don't think your best friend should be treated like all your other friends, because she's not, there is a whole different level of familiarity and respect and long term friendship. Definitely talk to your therapist, but also talk to both your best friend and your husband.
I'm not sure what you mean by go "on dates" with your best friend. Going out to dinner and/or a movie or whatever with just your best friend is normal best friend behavior.