2 girls in the same pledge class are dating

The same thing you would do if she was having a boy over all the time and it was making you uncomfortable. Tell them you signed up for 1 one roommate not two and that their PDA makes you feel uncomfortable in your own room which should be your sanctuary.

What a horrible situation. You shouldn't be in charge of a secret. You shouldn't be uncomfortable in your own room. No ones girlfriend OR boyfriend should be in your room all the time.
As for your house, I think you should encourage her to come out. Most houses here would not feel comfortable having dating girls in the same chapter. You could be caught up in keeping the secret when it comes out. And trust me it will.

Talk to your roommate when the two of you are alone. Just like you'd do if her boyfriend infringed on your privacy. Be nice, but firmly tell her that they need to go to the roommate's room or find another place to hang out. You are entitled to be alone or just with your roommate. If that isn't effective, talk to housing and document what steps you've taken. Counsel your roommate to come out of the closet and let her know you no longer feel bound to keep her secret.

Mind your own business

Agree with no 1. You have to talk with your roommate right away. Don't wait any longer.

Tell her you need your personal space and to host guests in another area of the building. If you can't tell her face to face write it down and hand it to her. Keep it simple. This is a fair request

Lol at some of these comments saying to out the roommate. That's bama for you

"I feel SO uncomfortable in my room, they are in the room ALL THE TIME"

That's the only part of your post that's relevant and what you need to deal with. The rest is just gossip.

Talkj to your RA. She's trained to help you his.

fake post

I kind of agree with #4. You shouldn't be bound to keep a secret, but also you shouldn't gossip. If someone asks, tell them to ask your roommate but don't lie for her.