Confused women

I have been in a relationship with my guy for 18 years.I caught him talking to other women on Facebook and dating websites, which he lied about it repeatedly. I gave him a choice to stop or I would leave him.he said he would but I found out about this women that he chats with on a regular basis that he thinks I don't know about to this day.the women had found out where I live and and been by my house.I ask him about her and he lied to me again.I told him if he wants her he can leave me alone and be with her.I have not did anything to him to be treated that way, he claims he love me but I just don't know anymore. Our relationship is strain and I feel some type of way.I think he won't leave me is because he knows I am a good women.I do not like how he makes me feel and now I am second guessing our whole relationship. Please help me make sense of this....