No you should wear it if you want to! In the long run you learn to cherish the good times and remember the happy memories instead of focusing on the negative therefor in the beginning IF you do breakup it may hurt a tad bit but then later on you wouldn't even care about it anymore and will see it as a good memory. I feel that way about many breakups in my life. I've learn to remember the special moments and not focus on how it ended or the bad parts.
well first of all-why are you expecting a break up? that's really not the right mindset when in a relationship. but anyway-even if you do break up-you'll still have the good memories,always remember the good stuff,and that necklace is a representation of a part of your life.