There's been some brilliant advice on this thread Wibhay
Read what Suddenlyseymour said again:
It starts off the roller coaster of anxiety - the regret is almost instantaneous, and it is such a MASSIVE handover of power, such a huge ego stroke for him, and you can't take it back. You will then be checking your phone CONSTANTLY, it pulls you right back in, if he doesn't respond you will feel even worse, if he does respond you get pulled into the whole dance again, it's AWFUL, and you end up back at square one having to go cold turkey again
She's exactly spot on with this. If you contact him, all the healing you've done and progress you've made so far (and you have, even if you don't feel like it) will have to be done again from the beginning, and then some. All you will be doing is prolonging your own agony.
Give yourself a chance. It's going to feel shit for a while. But the way to feel better isn't to throw yourself back into the lions den. It's to be gentle with yourself, to allow yourself to grieve, and to get back on with a life that you deserve.
Come on. You can do this. Tough out this stage and you will feel better before you know it. 