Guy wants to hold on to two girls

Hey. I need insight/advice.
I used to be involved with a guy for 1,5 years. We agreed to be friends when one of us met someone and we would break things off.
He did something stupid though, he lied to his new girl and said he hadn't been involved with someone for 1 year. When he ended up telling her the truth, he had to delete me from Facebook to prove to her that she didn't have to worry. Which means he lied again, because his plan was to be my friend again. He called me to probably expect that I'd either wait for him while he was "not being my friend" to that girl, or he expected that we would sneak around behind her back, which is so stupid because he isn't able to be dishonest for long, he always has to come clean eventually.
I tried to cut him off when I found this out, because I knew she wouldn't be ok with us being friends, and I know he will pick her. But then I wasn't able to cut him out longer, I asked him to fix this.
But there's probably no chance he will be able to have her be ok with our friendship. He is really smart but he makes such stupid choices. On the phone he was really trying to not loose me and said he would try to talk to her. But honestly, he won't be able to fix this. He's made it so we would never be able to be friends and her ok with it. Am I right or wrong? I'm really emotionally affected so I don't know if I'm thinking of all the options. Anyone , any advice please.