Up to you.
I've let go of a few people. Sad, but it gets to the stage where if I have nothing they want, and they have nothing I want then it's a but if a no-brainer. If the friendship is just built on wishful thinking then it's just a recipe for hard-feelings, and pretty much like sowing seeds of resentment to harvest at a later date.
There is a saying: When you find yourself in a hole, stop digging. And this step is simple, this is the point when we decide to put down the shovel and assess how deep the hole really is.