Whatever the outcome will eventually be, you must let go of him as if he will never come back. By doing this you release yourself from the state of anticipation which is making you feel that life cannot go on unless he returns. Life WILL go on and this is what The Universe is giving you the opportunity to recognize.
You still have a responsibility to yourself to continue your personal journey. Remembering this will allow you to keep going (and growing). It will also send a very important message to your ex-lover that you accept relationships into your life only as an enhancement and you do not become dependent on them.
Not only will this be a liberating experience for you but it will keep you in an emotionally healthy space, which makes you even more attractive! Releasing him as if he will not come back is a win/win method since if he does return to you, you can welcome him with a truly open mind and loving heart -- because you've kept peace and balance in your life while he was gone. This will ultimately lead to a healthier relationship in the future.
And if he does not return, it’s okay because you've already set him FREE, in turn setting yourself free to be open for new love to come into your life.