HI, it sounds like you are having a rough time recently. I hope you are having some better times occasionally.
I don't think you should get rid of the friendship necklace. It is important to you, just as the person was and is. Why not make a special place to keep it? This is a way for you to honour that person, without having to keep it on you, allowing yourself some space.
By taking that space, when you come back to the necklace by taking it out of the place, to hold for a while, you will be able to honour the person more deeply by focussing on them for a time.