Fighting again

I'm afraid that Mr. J and I won't be ok. Sitting around wallowing in regret after another all-night fight. Texting argument, really.  Insecurity is why.....my fault that, because of my past treatment of him what with the secrecy about the feelings I still had and acted upon with that ex.  Now I hate myself again....
I also hate how J goes from being incredibly supportive, so much so that I feel safe enough to tell him anything, to being malicious and spiteful.  I guess I deserve that to a certain extent, but it's not something I want to keep in my life.  How long will this continue?  I'd be very sad to lose him because of this.  But we can't keep poisoning each other.  It doesn't matter how upfront I am....he gets a feeling that there's something off about something I've said, and his insecurity goes through the roof.  Then we end up arguing....him insisting that I'm lying, and me trying frantically to convince him that I'm not and that I love him and don't want to be with anyone else but him. 
I don't deserve the luxury of complaining about this....but I just can't stay stuck here in this place of no possible redemption.  He likely doesn't feel that I am capable of honesty nor of loving him....I'm afraid he'll never forgive me.....But at some point all of this punishing has to stop because he's pushing me away.  Soon I'm going to give up on him because he's got this shadow over me that isn't conducive to the growth of love.  I feel as though I have such a nerve saying that, because I was dishonest in the beginning....if I'd known how much he would mean to me and how much I'd miss him after we broke up, I wouldn't have resumed anything with the ex.  This relationship was forged in uncertainty....now I'm stuck hating myself for hurting him. 

.....although....part of me wonders if he'd be insecure anyway, even if I hadn't cheated.  

But here we are again....no matter what else is going on in my life, the focus is disproportionately on J and what he feels.  Not to sound cold, but this is why I began avoiding him the first time around.  I'm afraid that no amount of holding and attempts at reassuring him will ever be good enough.