Can he stop?

Hi..my husband and i have been married 30 yrs. We get along great but the sex is lacking. Hes went years not even trying for it always falling asleep or drinking too much. We made love 5 times in 4 years..no kidding. He told me hes not young anymore and has trouble getting in the mood. Hes 54 i am 50..i always want it and he knows it. So recently sneaking a peek at his laptop i found his account for craigslist that he didnt log out of. There were 75 posts spanning over 10 years looking for sex from others within 50 miles of home. He posted ads looking for casual sex with women, men,couples, preferrably married. I am fit and he asked for BBW. Hmmm.. needless to say i busted him at 3am from a sound sleep and he was obviously scared. He insisted it was for fun..the thrill of seeing who would answer his posts. After arguing it out he confessed to meeting 3 ppl..all men. One came to our house the other 2 he met in a town closeby. All 3 occasions he said he backed out from guilt. The man that was at our house he had to get rough with via email because he said he wouldnt leave him alone. One craigslist post said.." to the lady who sent me the pic of your nice tits send to me again and we'll go from there". That sounds serious to me. He said he doesnt remember if she wrote back. Long story short..our relationship sucks now. He acts sneaky and i dont trust him. Hes always deleting activity on his internet history but denies it. To top it all off..i found him on at least 6 dating sites registered as married looking for discreet sexual encounters. Hes a respected business man noone would ever suspect of this. It explains the lock on his phone for all those years. He claims he never once touched anyone just did it for curiosity. My question ..besides why the hell havent i left him yet...is...this was more than just curiosity right? can he just abruptly stop this game or has he just found hetter ways to hide it? Now that hes been busted hes a little nervous since he knows ive tbought about leaving. He said he doesnt know why he did it. He claims he hasnt went back to any dating sites or craigslist. Hes also very good with a computer. He avoids talking about it and when we do he gives very little information. I need advice..or a wake up call..one or the other. Can someone tell me as an outsider wth happened with what i thought was a fairly good 30 yr marriage? I hope so. Thank you so much!