Most of you are going to do better during the day than you do at night, particularly the later at night it gets. You've probably already noticed this phenomenon. It's just true that the wee hours are harder and we're going to have to work with that. One simple but beautiful thing to remember is that no matter how bleak the middle of the night seems, dawn is on its way and can't be stopped.
1. Do Not Call Him
Whether or not you should contact him in general is a larger issue, but it's never a good idea to call him in the middle of the night. (For these purposes, the middle of the night is any time from 11pm to 8am.)
Take, for example, my friend Lucy. She will keep you on the phone for hours going over why she is not-not-not going to call her ex even though she is dying to do it. Eventually she will say the coast is clear and she is going to bed. By now it's usually around 3am. She will hang up the phone with you. She will then wait about five seconds and call him. He will be sleeping (surprise!), and their conversation will inevitably be disappointing to Lucy. She will then freak out for a few hours, smoking a carton of cigarettes, and call you back hysterical at the crack of dawn. While this is a very common scenario and I've played it out myself several humiliating times, it's not good. I have never ever known anyone who has felt better after a wee hours phone call to her ex. It's unlikely that you are going to be the first.
Also, it is quite possible that your judgment is not so great right now because not only are you tired and emotionally strung out but also maybe you've had a few cocktails or a few brewskis. Here's the deal: Never drink and dial.