There's a thing known to psychologists - romantic attachments that form between 13- and 16-years-old often last for life - whether toxic or not.
So if you're choosing to stay together, your best bet is to discuss the idea of growing out of toxicity and into maturity together.
I can recommend several paths that helped me enormously.
Using all of them simultaneously would help the most.
Vipassana meditation. The 10-day courses are free - you give a donation according to your means at the end. They teach how to develop mindfulness - this is the best way to become more aware of feelings before blurting them out in ways that might hurt one another.
Codependents Anonymous. A free 12-step fellowship which helps participants let go of trying to control others, and learn healthy boundaries and self-responsibility.
Although it advocates coming to believe in a Higher Power of your own understanding, atheists can choose to rely on the group ( the fellowship). There is no restriction on what your Higher Power might be. It could be Unconditional-Loving-Kindness or just Love for short.
It can also provide access to a wealth of relevant self-help books.
Daniel Goleman - book - Emotional Intelligence
Marshall Rosenberg - book - Nonviolent Communication - a simple four-step method for listening, communicating and finding mutually agreeable solutions. It can help to join a free weekly practice group. There are videos of the process which can be watched for free on YouTube. Rosenberg himself is a little hard to look at, and the timbre of his voice is not that pleasant to listen to - but if you can get past that, the content of what he offers is brilliant - pure genius and all heart - a passport to functional relationships of all kinds.
Wishing you all the best. :)
