I think this is a really keen insight (bolded part). It seems to me like your T has a sense of what the "finished product" might look like (especially after reading his email), which is that you will arrive at a nuanced understanding of your mom's perspective, with her own strengths and limitations as a parent, and a sense that she did the best she could, even if she ultimately couldn't give you what you needed. But it seems like your T doesn't have a sense of how to get you from Point A to Point B. It's a long road of healing that requires subtlety and skill, and he seems like a bit of a bull in a china shop here. It's one thing to know these things about your mother rationally (you probably already do), but it's quite another to build up a solid enough sense of self where you can hold onto your perspective and her perspective in a meaningful way. The big hurdle there is accepting yourself and your entire experience first. Until you can get there, his exhortations about forgiveness will just feel like more pressure and judgment. (I would also note that estrangement is another option. I'm not saying that that's desirable or recommended, but it seems like he has already decided what your future relationship with your mother should look like. That took me years to decide for myself.)

I'm trying not to comment as much on your thread these days because I think you perceive me as being hostile or not a fan of your T. I actually think he's a decent therapist, but I think he's probably not a good fit for you (maybe like your parents?). He seems to have some pre-conceived notions about where you are and where you need to be that are likely restricting your growth. I talked to my T a little bit about your situation and whether she thinks it would ever be helpful to say that a client is too sensitive, and she said that that phrasing seemed like judgment and that she would be far more interested in knowing why the client is sensitive about things and where it came from developmentally. I felt the same way about his comment that you were a difficult child. It's not terribly helpful to contextualize it that way and likely does more harm than good, but it seems to shed light on some of his perceptions of you.