-Uber doober ultra mega hugs!-

If you were not human you would not feel such emotions. And unfortunately for people of all ages. All you described in your days after a failed relationship I too have felt on more than one occasion. And I finally learned that you can't love someone unless you love yourself. If you did that and exhausted every effort to try and maintain your relationship then. Guilt should be at the very bottom of your emotional list.
It'll pass if you let it.. In the mean time focus on you.