I haven't been in this exact situation as my T doesn't share feelings much with me but I have shared some of my strong feelings with them.

Like you, when I do share vulnerable feelings it can feel good and appropriate in the moment but a bit 'ick' and uncomfortable afterwards. I think this is what Brene Brown means when she refers to what she call a vulnerability hangover. The feelings that arise after we share something deep and vulnerable can lead us to feel exposed and it can be a little scary especially if it is not something we are used to doing or have been hurt a lot in the past. For me it feels like a bit of a dangerous space.

I'm glad your T was able to respond to you and accept your vulnerability openly and with care. I can understand though how her response may bring up mixed feelings. How would it have been if she had not responded back? I would try and lean into the nice feelings and let go of the discomfort but thats far easier said than done I know.

Talking about my vulnerability and the fears with my T after I've shared something intense and having her listen and reaffirm that it was ok and nothing has changed has been helpful so maybe speaking about it in that way might be useful?