That she said it was a terrible experience speaks loud and clear the amount of stuff she has buried. I doubt 8 sessions is anywhere close to enough. I would think a year at the minimum is needed. She might have to go alone for most of those sessions to open up to the counselor. Since she needs to work on her issues, you don't really need to be around, and being there probably makes her clam up.
But your attendance either jointly, or in your own private sessions, may be needed to induce her to go. Her clamming up is evidence of how defensive she is about discussing her issues, so I think you should avoid making her feel like the focus of the needed therapy. She probably has a lot of shame surrounding this too, so you need to tread lightly, but I would push for the counseling an not stop until she agrees to attend. I think it could be that important.
