You should know what you want. You don't want someone who is going to be flaky, you want someone who is honest and trustworthy, someone who knows that they need to do the right thing. Be honest but don't get all wishy washy with feelings, etc.
Tell her that for you to trust her, she needs to show consistent trustworthy actions and it isn't an overnight process, this is something that could take weeks/months... years. It's up to you, your internal bs meter should know what she's like, when she's lying, when she's honest, etc.
Also tell her this, you don't want to be a punching bag, you won't be taken advantage of by her anymore but at the same time, you don't want a punching bag for a wife, someone who you have to beat up and teach a lesson to. That's not fun.
Also tell her that you don't want someone who is going to play the victim with that rehearsed bull$hit line she fed you above. She can be sorry for what she did but when she says it like that, she almosts wants sympathy for what she did.
You don't want to crucify her or judge her for the rest of your life and if she thinks that's what you'll do to her then educate her and tell her that's why you can't take her back right now, she doesn't have the right mental image of you: you're not the bad guy and you don't feel the need to beat up people and make them pay for the rest of their lives for what they've done. You can tell her she's not a bad person, she just made some bad decisions and you won't hate her because of it - you're a better man that that (I'm assuming you are, you should be), a real man doesn't hold grudges forever - that would like living a limited life and that would suck.
