I'm not sure if this will fall under the 'bashing your SO' category; if so, feel free to delete, but I honestly don't know how to phrase this in a 'neutral' way, and I'm in quite a bit of shock ATM.

I found out tonight (via an e-mail that he didn't mean to forward to me) that my husband has been soliciting sexual banter/sending pictures of his penis on Craigslist for the last 2-3 years, and also writing personalized erotica and sending it to women he 'meets' on CL, and they write him back erotic replies. When I came to him looking for answers, he claimed that he has never physically or emotionally cheated on me, has never met anyone in person, and that this is a 'compulsion' for him (along with watching porn, apparently). We've been together for 7 years, married for nearly two, and there's a very strong possibility this 'compulsion' has been going on for our entire relationship – I found him dirty talking with a random girl on FB about a year in (forgave him for that, he swore it wouldn't happen again; and to my knowledge, it didn't), then an e-mail similar to this one about a year ago (which he again swore was a one-off; of course now it seems that wasn't the case), and I'm just feeling completely lost.

It's like my Captain said we were heading for the Bahamas, and I woke up to find we were on course for the North Pole.

I just don't know how to respond to this; it feels like I'm the one that messed up from the way he's acting, even though it's his transgression. He doesn't seem to be taking it seriously, or really acknowledging that I have grounds to be upset about this; it 'didn't mean anything'. I'm now wondering if this might be the reason that he sometimes 'doesn't feel like' having sex, as that has been an on-and-off issue throughout our relationship (he has always stated stress as hurting his libido, and as his school/work are both stressful, I've never even thought to question it – my libido is naturally high, and I do NOT turn down sex/actively try to proposition him even when knowing I'll be turned down.) I just don't know where to go from here, in terms of not leaving him. That would be the expected response to something like this, but I just don't think of that as an option. I don't even know if I consider this cheating/a breach of our marriage vows or just an addiction of some kind, or somewhere in between. It's very confusing.

A little background: I'm a housewife, he works full-time outside the house, we have no children (but do have two dogs), and other than this new revelation and his somewhat low libido, we are a very RP couple - he's actually the one who introduced me to the whole RP/manosphere in the first place, and it just 'clicked' with both of us.

Any advice/insight would be so, so appreciated (as long as it's not 'leave him!')