She's actually right, or at least following the advice that many are given here --
the wayward partner works on themselves, figuring out WHY they cheated, working on and FOO issues they have, self-esteem issues, the need for external validation, etc.
the betrayed partner works on healing themselves, because many show signs of depression and/or PTSD (or PISD: post-infidelity stress disorder), such as
Behavioral: agitation, irritability, hostility, hypervigilance, self-destructive behavior, or social isolation
Psychological: flashback, fear, severe anxiety, or mistrust
Mood: loss of interest or pleasure in activities, guilt, or loneliness
Sleep: insomnia or nightmares
Also common: emotional detachment or unwanted thoughts
"Unwanted thoughts" are often referred to as "mind movies" on SI, and have a habit of popping up, unwanted at the worst time. For example, I usually get hit with them while having sex with my WH. The image of him having sex with his AP pops into my mind and just... I gotta stop and cry.
It's also not unusual for your self-esteem to take a beating. My WH's AP was 10 years older than me, 3x my size, and not pretty. She had buggy eyes, a weird shaped forehead, and always had fake hair and nails and a ton of makeup on. So at first I would look at pictures of her on facebook and think that there must be something wrong with me that he chose HER.
But no. The problem was him. There was something wrong with my WH. That's why he had an affair, and told himself things like, "it's because I'm so hot AP couldn't resist me," and "big girls need love, too, so by sleeping with someone her size, it was almost like doing her a favor."
Meanwhile the AP got her self-esteem (temporarily) boosted, thinking she must be so attractive that she lured away a married man, until... he dropped her like a hot potato.
Anyways, your WWLTGF should be working on herself, because her cheating shows that she has issues, not your relationship. If/when she figures out why she cheated, then she can work on that part of her character and firming up her boundaries so this never happens again.
Tell her that you're not going to wait around forever, that you need to figure out what YOU want to do, but maybe in the future if she works on herself, you might be open to relationship counseling and fixing your relationship.
BUT.
Take your time. Go to therapy on your own. And think about what boundaries you need to set going forward.
Not to control her, because that never works.
But, for example, "I will not be in a relationship with someone that has contact with their ex-AP, ever again."
So she needs to commit to going no contact, and and she needs to understand that you're not trying to control her, but you're setting boundaries for what you will and won't accept in any relationship that you're in.
Has anyone else recommended How to Help You Spouse Heal from Your Affair by Linda MacDonald? It's inexpensive and a short read. Tell her if she doesn't know where to start, she should get that book to get an idea.