What I would do is print out all of the correspondences and keep them to confront him when the times comes but I would ask a friend to take you to one of the meeting places with these women the next time they set up a meeting and the time and place have you friend take you there and be waiting this way the proof (the woman) will be with him. Before you do all of this you have to have a plan of where you are going to go or how you are going to get him to leave if that is what you decide this you have to think about first are you going to take him back or are you going to leave him or have him leave? If you do not have a friend then take a cab but act as the other woman make plans to meet at a hotel you go to the hotel first and set up everything like it's going to be a romantic sexual encounter and tell him the door will be unlocked and then have all the correspondences laid out on the bed and be waiting in the bathroom and when you hear him come in confront him with the proof.
One thing you have to realize is do you want to be with someone you can not trust? How are you going to be able to get that trust back? You can not let this go you have to show him that you know what he has been doing and that you even corresponded as one of the women so that you could have concrete proof that he is cheating. It really doesn't matter how you found out what matters is that you found out and have proof and he needs to be confronted with the truth and you can not do that without setting him up as if he is meeting a woman off the internet if you just confront him at home he may lie and say he never met them this way if you actually shows up then you know he has done this before.
Afterwards if you want him to leave be very clear about what you want and what the next steps in your relationship will be and make sure your friends stays there with you in case things turn ugly, you will have a support system there already. Usually I don't believe the saying "Once a cheated always a cheater" but if they do it over and over again more than likely they will continue to have this behavior. Do what is best for you now!
Even though you knew how he was he promised to change for you and the fact that he hasn't shows that he doesn't respect you or himself he continually talks to other females online and disrespects you constantly without even giving a thought to your feelings is this someone you want to spend the rest of your life with? Life is was too short to live it for other people; you have to start to think about your happiness now. Do you have family you can move in with? I think you should still print out the correspondences with other females and about the meetings and show those to him and then you have to make up your mind as to whether you deserve more. Don't settle because you have a disability he could make the disability worse because stresses tend to make illnesses worse instead of better. You need to be with family or friends that will care for you and respect you enough to consider your feelings?
Your live in boyfriend is only thinking about himself right now and his needs and yearnings without even giving you a second thought, if he really cared about you he would tell these other females about you and be honest with them about living with you and then allow them to make the decision as to whether they still want to meet. It seems his deception and lies have become common place for him now and so easy for him to do without even thinking about the consequences of his actions, that is what a player is someone who only cares about self and tells women what they want to hear in order to get them.
The final decision is yours to make but you really have to consider if your boyfriend is a positive or a negative in your life. Don't stay because you feel stuck you have family and friends that will help you, you need to show him that you know what he is doing and either give him an ultimatum to clean up his act or you will be leaving and if he doesn't pick the ultimatum than you will have to make arrangements to leave the relationship for your healthy as well as your mental well being.
Thank you for your accept and I don't need a bonus just my being able to help is enough for me. Could you leave feedback as to my performance just click the feedback button it is free and no charge.