My mom once said / did a similar thing to my alcoholic sister--she took my sister to the alcohol aisle at the supermarket and said, "well, pick out what you want--let's stop hiding this!". AS, needless to say, was not amused.
But anyway...I find that 'huh...I'll think about that..." and changing the subject--usually something to put the focus back on the other person--works well with unsolicited advice. And then just drop it out the other ear and go on your merry way. IMHO...some topics are like politics; even with well-meaning friends, you just can't talk about them. I have a good friend who is on the polar opposite spectrum politically than I am...and we just don't go there.
Sending you hugs...