My dear, I have not been through what you have experienced, but I have an admittedly hypocritical piece of advice that I wish I could accept for myself- just tell them. Do not allow them to go on without the missing puzzle piece, it is an injustice to them as much as it is to yourself. Allow yourself this closure- it may feel like ripping out the old stitches you have sewn, but the act of healing is so much more deeply rewarding than the artificial solution you have created.
Healing will hurt, but it will do just that- help it heal. Re-hashing these memories by continually internalizing them is nothing short of self-abuse.
I would love to know more than anything what you decide.