Well, it sounds like you already know that they're not good friends. I'd drop both of them as it sounds like they're both toxic. They probably talk about you behind your back too. I wouldn't trust them anymore if I were you.

You can talk to them both and tell them if they don't stop their immature and dramatic behaviour, then you can't be their friend anymore. Tell them that you're sick of being caught in the middle. Do it nicely though. Why are you even friends with them? You need to make better friends who are more positive, mature, and respectful of each other and yourself. Forget about them and move on with your life. You'll be happier in the long run.