Why is my girlfriend saying these things to me?

My girlfriend has been saying that she likes holidays. She told me that when she was with her ex that she went on an 18 - 30 holiday, but lied to him saying it was with first choice or something. Basically she is telling me she is a liar. Also she has said that she gets bored. Told me that she gets a lot of attention when she goes out. I don't understand why she is saying this to me. Went on to say that her ex was crying when she dumped him, and told me she has dumped everyone she's been out with. I have spoke to her about this, and her going on holiday. I'm always thinking that she might be lying to me. She then says that i don't trust her and maybe she is not the right girl for me. She makes me feel like i have a problem. Also she has told her friends and it looks like i don't trust her. She comes across as very friendly and nice but then she says these things that get me thinking. Also she tends to get the sulk over small things, and she gives me the cold shoulder. I feel like i have to be careful with everything i do and say in case she gets the ump. Im living on egg shells with her.