There is a wise poster on here (Dandylion) who has the best definition for co-dependency......
Co-dependency is most about a lack of relationship with self, rather than about our relationship with others. I found this for me to ring very true.
Digging into my lack of relationship with myself was very helpful. I was disconnected from my feelings. I was interested in others so I did not have to feel my own feelings. I found Al-anon, reading about co-dependency and other topics and therapy to all be helpful in my healing.
I had the difference between guilt (upset about a behavior) and shame (upset about myself as a person) to work through.
I am most of the way through it and life is so much better.
This is an aside but I find the work of Esther Perel, especially her podcast How's Work very helpful now and I think I would have when I was in the thick of this. Esther believes that our family of origin stuff and wounding that needs to heal particularly presents itself in two places, the workplace and in intimate relationships.