Thanks for the clarity confusion. That other thread that was active this week was surely yours then wasn't it? All the details were identical.
Only you know whether you can't resurrect your feelings for your husband now. It sounds as though you think you cannot. In which case, I think you've got two options. Go to counselling on your own and suspend the decision, while remaining NC with the OM - or bring this to a swift end.
It's anyone's guess why your husband seems ambivalent at the moment, but it's not unusual at all someone to feel extremely ambivalent about a partner when he or she is having an affair. That tends to end as soon as an affair is admitted or discovered, but it doesn't sound like you want to disclose.
Regarding other posters' comments, I mentioned on a thread the other day that I often feel out of step with some of the received wisdom on this site, especially in situations where there are shades of grey. For example, the stock response from some on an infidelity thread is to leave and not forgive, regardless of the circumstances. It's the same with one-off DV, where the circumstances are far from clear-cut and has been committed by a person in extremely unusual circumstances.
As someone who has seen couples work through single episodes of infidelity and low-level DV, I would feel inauthentic and irresponsible joining in with that chorus, when my experiences in life tell me that there are nuances and often other factors at play. I've seen couples stay in a loving marriage when one of them has hit out once because of physical pain, or a meds. clash where their mind was chemically altered.
I must stress that this is completely different to any violence where the only context is long-tolerated abuse that has escalated, or sexual violence of any type. On those occasions, I entirely support the one-strike-and-out philosphy. And I think posters' support for women's choices to leave in those circumstances is magnificent and I've often added my own support to those threads.
Equally I don't blame the OP here at all for feeling that something was irretrievably broken when this violence occurred, especially with the facts that are available now.
But what I'd also say is that it doesn't matter why you want to end your marriage - any reason is enough - and there are evidently more reasons than the DV, some of which are of your own making. The only reason you need though is that you don't want to be in the relationship any longer and that your feelings are not strong enough to stay. That's okay and perhaps you need to give yourself permission for that.