24 year affair - secret lives - "I have no idea who I am or what I want"

My husband had a 24 year affair with a married co-worker I despised. She stalked him, moved in close proximity to us, commandeered our social life, belittled me in the community, and accosted me every time I ran into her.

She pretended to be me, dressing in similar clothing and taking on my hobbies. She trespassed on our property multiple times, looked through, stole and destroyed personal belongings.
We moved out of town, and I avoided her and certain social groups.

I thought she was a comical neurotic who flirted with as many men as possible. I trusted my husband, even though he was distant and critical.
Years went by.

Our very aware college-aged son was suspicious of her and confronted my husband, so I ended up finding out about the affair because my children told me! My husband called the affair a fling they had after she was divoriced.

I wanted to stay in the marriage, but was devastated. The trickle of truth made each day a new disaster. When coerced ten months into reconciliation, he admitted spending ten years with her.

After another year-long investigation that included speaking to the affair partner, her ex-husband, and the wife of the man she was currently with, I screamed at my spouse to "start at the beginning".

This resulted in the discovery that the affair had lasted 24 years, starting when I was seven months pregnant with our second child.

The mistress has broken up three marriages in the same fashion - invading lives, and imitating the persona of the wife. She is neither regretful or apologetic, but extremely obsessive and unbalanced.

Her ex reported that she had multiple affairs during the time she was married to him and involved in the affair with my husband.
My husband wants to stay married to me - claims he will be forever sorry, that the affair wasn't about me.

It feels like abuse. He mentionined what a toll this has taken on him. He wants to retire and have a "smaller, predictable" life.

I understand how difficult monogamy may be for some people, but I was faithful and committed to the marriage even though I was unhappy for many years. I feel I was robbed of so much time and now am stuck in "unrecovery".

At first discovery, I stayed because I did not want this woman involved in my sons' lives and because I still loved my husband.

Nearly three years have passed, and I have functioned at a high level, yet I have no idea who I am or what I want.