Defer to the aspects about yourself that you enjoyed before you were with the person. Get back in touch with that part of yourself again. Go back to your hobbies, they are great distractions. Time heals all wounds, even if they take years to stop bleeding. Start focusing on yourself more seriously, utilizing the new amount of time that you now have to try to make improvements on your quality of life for yourself. If you're lonely, maybe spend some time with your pets, or get a pet if you can. If not, there's always the people on this forum who are also lonely people. If you make it a priority to forwardly deal with your emotions rather than trying to ignore them, than it will be more upsetting, but it will improve faster. And lastly, and most important to remember: Always forward, never backward.
I walked out of an 8 year relationship about 4 years ago...while I was still in love with the woman. So believe me, I know how hard it can be. I'm over her now. It took me about 2 years to completely get over her. So it IS doable. As much as I loved the woman, we grew into different directions, and it just wasn't working anymore for either of us really. So, I had to be the stronger one and make the better judgment call for the both of us. We're still friends. We just rarely talk. In part, because I dealt with it forwardly, and she is only just now trying to deal with it. We've had all the arguments, said all the things to say. And we made it through as friends. I'm respectfully giving her the time she needs to deal with it. I have a feeling that when she's finally dealt with it and over me, that we'll be talking semi-regularly again as friends.
It just takes time.
One day at a time.
Baby steps will get you a long, long way.
Sleep helps. It resets the brain a bit.
Good luck. Peace be with you.
Don't make any irrational decisions. This is only temporary.