Did this friend move from Ireland with you? I suggest you learn now, while you are young, that no one can control your life or your friends unless you allow it.
If you want to talk to the other girls then do so, if they don't because of this girl, then I suggest you find friends with a higher level of maturity. Thinking so low of yourself to allow this person to cheat from you and then still tolerating her abuse tells me that you could use some counseling for your own self esteem.