If she and the dogs can get by without seeing each other except for one day out of every 2 or 3 weeks, then I'ld say it's time to cut that connection. What she's doing isn't healthy - for herself, for the ex, or for the dogs. This is not about the dogs. That's just a smokescreen. This is about her continuing to have an emotional connection to her ex. She doesn't want to totally let go. Their bond goes back to youth. It sounds like it became almost a brother-sister type of relationship.

After 5 years of seeing a therapist, she is still going to this same therapist to address things from her past. This is a lady who has a major problem with living in the present. She wants to keep churning the same things over and over. That's not how you make progress.

I think your instincts are correct. It would not seem unreasonable to me for you to tell her that she needs to cut this cord to her ex, if she wants to have a future with you. Otherwise, look at the problems that you can count on coming up. Eventually, you and her will have little difficulties in your relationship, as happens with all couples from time to time. Well, once or twice a month, she will be in the company of a man she has a history of being intimate with. Guess what she's going to talk to him about. Yup.

You don't need a third party hovering on the periphery of your relationship like that. No sane person would want that. Her therapist should have given her the same advice already. To be honest with you, I think it's time she cut this therapist loose too.

By the way, next time she offers to let you read her soul-searching writing about her past, decline the invitation. This material that she has shared with you is diary type stuff. That's not appropriate material to be sharing, as you found out when you read the stuff. Let her write you some love letters, if she wishes to use her writing talent to deepen the relationship.