Unfortunately I tend to be too forgiving and accepting of hurtful behaviour....I don’t know if humans can change who they fundamentally are?

It's okay, I am too, it's something I'm working on. One important thing I learned is that "forgiveness is for yourself." Which means, do not feel like you have to forgive someone just because they apologized, only forgive someone if you actually want to forgive them. I think that helps a lot.

I do really believe people can change who they are, however I also understand that people have to want to change for themselves. So I always have the belief that people can change, and I also acknowledge people may not want to change. I have to accept that and move on with my life. If somebody doesn't want to change their hurtful ways, then they don't get to be part of my life.

We’re all a product of our environment/childhood/trauma.....is that making excuses in so far as DV?

I don't know. I think what we can do is acknowledge that, yes, our environment, traumas, and childhoods do affect us in our present form and we can also acknowledge that being abusive is wrong. I like the quote "it's not your fault but it is your responsibility" when it comes to such quandaries. Meaning, yes maybe somebody had a traumatic childhood, and their abusive behaviors are not okay. Lundy goes over this in his book. It's not their past, it's not their trauma, it's not their environment that makes people abusive, people choose to be abusive.

I  feel pathetically grateful for him, a man, speaking so earnestly and assertively...probably a bit pathetic tbh (me, I mean, for being grateful) 🙃

I don't think you need to feel pathetic for feeling grateful. 🫂 I am also grateful that Lundy made this book. He has a lot of "inside knowledge" that women probably would never get about abusive men, because he is a man himself and men act differently around fellow men than they do when around women.