I'm sorry that this is so hard for you. Knowing that something will be hard when it inevitably happens doesn't always make the actual experience any easier, unfortunately.

I agree with what LT said about the timing of her sharing the news. Even if there were no concerns with this pregnancy, if she maybe had a very early loss before, she might be extra anxious about the reveal. It can be difficult to anticipate how fraught and stressful pregnancy can be until you're in the thick of it, so maybe she was surprised by her hesitation too.

As for the nurturing bit, I actually think it's likely that she will develop a deeper understanding of attachment and co-regulation and the importance of early childhood experiences once she becomes a parent. The process of raising a tiny human can really change somebody in remarkable ways. She seems very caring and deeply committed to her work with you so of course the break will be painful, but the resumption of therapy afterwards might be better than ever.

P.S. Even though you're hurting, I'm utterly impressed by how you're already trying to make sense of your feelings and work through your reactions. You seem like you're reaching for the right things: support from J, acknowledging your need for distance from L even if you ultimately don't decide to take it, using your wise mind. It's good stuff -- keep it up!