I guess the ? is do you have the space to keep it going. If you have limited space and light do you want this plant taking that space or would you replace it with something that looks more attractive for now. I have some of the same problems with some of the Houseplants I bring inside. I don't have a Eugenia but one of my good sized Hibiscus and a good size Bougainvillaea that did the same thing I think the Hibiscus pretty much lost every leaf but it is leafing out now. Also I think you are right about the pest problem maybe spidermite and then the ? is how bad will it spread to your other plants. If it was sitting near any other plants you should treat them also. So if you have the space to keep it and you have already treated it then I would keep it and see what it does.
