Sim, I'm just back from Lebanon after many weeks and catching up here... man, from the perspective of meeting my man's friends, it meant so much to meet them in his home country. I feel like I know him so much better now, and have a far better understanding of his social needs.
Well, I'm sorry to hear that things didn't work out for you, but it sounds like you two were eventually incompatible, at least at this time in your lives.
Continue being honest with whomever you are dating... as honest as possible, in a loving way. It's their responsibility how they will react to your honesty, but if you are honest, then you are above fault.
I think it's important for you to work on being honest with your SELF, though, right now. Your gf is out of your life, for good or bad. Now just work on you and what you want, including what kind of gf you want in the future. It sounds like whoever she is, she will have to embrace Sarah, since you are not willing to change that friendship.
Okay enough advice for now.
Good luck.