Adding to Cobis yeah what a terrible friend:

• who risked everything for Barry and lost the love of her life TWICE because of him and never blamed him/accepting responsibility for her/Ronnies decision to help him
• whose other close friend, who knows her even longer than Barry, fear/doubt her. And saw same close friend also hiding his powers from everyone
  To OP: who is the terrible friend?

Yeah, a terrible friend who helps you get out of a prison inside a mirror. Same terrible friend who spends almost her entire time assisting you in your fight against criminals without asking for anything in return.

having the same powers as an insane lethal criminal is not a small thing to hide around, when you hide it from friends you are not being bad towards them, you are just lacking courage to think like you is what is actually selfish, thinking she has to tell them.

She's trying to stay in the closet.
www.jrichardsingleton.blogspot.com

This Caitlin has been to E2 and has met herself. E2 Caitlin probably had more in common with her than she would care to admit.
She is probably worried, as was Cisco, that the powers themselves could turn her evil. How many metas have they come across who were given powers and chose good?
She probably also does not know how she got these powers. I hope that part is explained in a flash back the same way the show made it clear that Mirror Master and Top did not get their powers from Alchemy.
Flashpoint/Reverse Flash's changes may have changed her slightly. Something either happened to her or didn't happen and that change might make her more inward.
Then of course there is the notion that these changes are affecting her physical appearance. That didn't happen to Barry or Cisco.
Furthermore, these are powers which may prevent her from ever touching another person, ever again. Unless of course they have Firestorm powers.
She's freaking out. I get it.