Easy solution: Fix your priorities. How? Like this:
The more time something spends both in your mind AND in a nearby location, the more you should care about it and whatever affects it.
Note that "whatever affects it" can be located far away, but "it" has to be physically located close to you.
If something physical in your vicinity is affected by the continuation of your relationship, then the relationship is a priority, otherwise it is not.
Actually, ending up completely alone can be a very positive thing.
How do you identify yourself if not through the eyes of others? If you aren't completely satisfied with your answer to this, you need to spend some time completely by yourself.
Easy, let go of your ego.
There are two ways to do this.
Following this path, you will eventually see no need to control any aspect of yourself because you never had control to begin with. You will notice yourself as you do when you are dreaming.
Seeing as you think very lowly of yourself, this way will almost certainly fail. You would probably be way better off with: