My partner has been lying

My partner and I have had issues for some time starting with when I looked at his computer (we had trouble with an ex) he didnt ask why or what I wanted to know he joined and internet dating agency and started to send messages to other women when I found out I was told it was to pay me back for snooping a couple of weeks later a woman "pops" up out of nowhere and starts texting at all hrs (2am etc) I politely asked him to tell her to confine it between working hours I was told she was a friend and he would do it in his own time..then an email was discovered with a drawing(gorgeous pencil drawing of a sexy woman) when questioned I was told she was frumpy and it was a joke we went to couples counselling his instigation and worked thru it but the trust was hard to find..he was made redundant from his job 4 months ago and there is no forced redundancy so therefore he has heaps of time to troll the net i had a gut feeling something wasnt quite right (he had a breakdown last week) so I was very concerned tried to help etc etc but this feeling stayed so I had been given permission by him to look on his computer or his phone months ago so I did and found nude pics froma woman on the computer I calmly asked who she was apparently I was told he had known her for 15 yrs and was in love with her....absolute crap he lied cos he told me it was 6 weeks she rang him a few months ago and I heard him tell her that he was with me but obviously kept contact I was so angry and felt like I had been made a fool of again...when it got heated and shouting he told me it was all my fault because I didnt trust him....I had no reason to trust him he told me it was over and he had booked a ticket to see his sister (there were some family probs in between) but surprise surprise guess where the new woman is.....The same place as his sister..I am just gutted and in pain....I feel like a disposable nappy I loved this man and stood by him and helped him guess I am lucky cos its only been 18 mths but it hurts so much..I rang her very calmly and asked how long she had known him ..she hung up..I am not angry at her she s been led to believe something different obviously what is doing me in at the moment is this man will not accepts responsibility for his stupidity..I am not entirely innocent as I know I have made mistakes along the way too but I thought I would give him space (he was devastated when he was made redundant) i am finding it extremely difficult as I moved from my home state to here with no family or friends and now I think I just want to go home...Ihate what he has done to me but I have had issues to deal with on my own because he was incapable of making a decision I really dont know what to do?