Breakup Advice

I recently went through a tough breakup with someone I am not only in love with but who was my best friend and my main source of support. We ended things very nicely and even though it hurts now we want to try and be friends later on in the healing process. Because this was my first ever break up and it's my first time being alone in 3 years I have absolutely no idea how to deal with it? I have friends around me but being alone is hard and I know I need to have time to grieve but it feels like a horrible cycle of regret that it happened, blaming myself and then accepting that its the best thing. We've spoken a few times to try and clear the air so there are no bad feelings or feelings of guilt. I don't know what to do to occupy my time when i'm alone in bed? And I'm not sure what to do to move forward past this stage?