You don't have to fight his "constant convincing". You can choose to let this rest for awhile and tell him you need time and space.
Right now he's acting like a spoiled kid from whom someone has taken a toy, whaa, whaa, whaa, I want my toy back, Mommy(insert sponsor here) I've lost my toy and want it back, what can I say to get her back in line?????? I promise never to talk back again, to never have flings (that you can find out about), I promise to show you how special you are to me, I will love ya foreverrrr.... You are my truest love, blah, blah blah....
It's hard to step away and it hurts tons. It's hard to accept that we've been played. Life shouldn't be this way, but with this guy, it is. It is. I would toss my phone down the toilet before I'd reply to another text. Let him sqirm while you find yourself and your direction again. Each detour is another trip down misery lane.