waves hello OP!
Well, your thread was a breath of fresh air! I can feel your anger through the screen - but also your strength. I wish I had done what you have when I first had suspicions.
I posted my thread in 2013 a couple of days before I dumped him. I should have dumped him in 2009!!!!!
But I had a new baby, no evidence, a complicate work situation... blah blah blah.
I did my own (sexless) thing for 4 years. I wasn't suffering day to day... but I was overall. And oh the destruction to my dignity, scraping around for evidence!
When I finally chucked the cunt (3 year dumpiversary tomorrow!) he said he was only looking. I said "and only looking is enough for me to leave you" - and meant it.
Trying to ignore my bias, I'd say OK - there is a chance your arse of an ex was "only looking". As you say - that's a dumpable offence, who wants that?
But what would "justify" your decision to me anyway, is his reaction. Where is the understanding that this is devastating to you, the attempts to reassure you and fix things? Nowhere. Because he's a shit.
And everything else you added (my XH also shit in bed) well - why would you not send him packing?
Frankly, go you!
Three years on, and I can tell you that I'm happy, my child (same age as your eldest when this kicked off) is perfectly happy with two homes, and we coparent with surface civility 
I can also tell you that I'm engaged... But I almost don't want to because the success story is being happy, and I was happy single without XH's shit.
Oh - I did find out unequivocally a short while after that he'd been fucking prostitutes throughout our whole 8 year relationship 