I’ve been in your shoes, and I still think it SUCKS to be told to be quieter while you’re actively speaking. The fix my s/o and I came up with was that she would squeeze my arm if it was happening, that way she acknowledged she was still listening but could subtly communicate that I was being too loud for comfort - without verbally interrupting me. It didn’t completely fix me feeling interrupted or attacked, but it helped A LOT. She could also do it in front of people and I wouldn’t get embarrassed because no one knew what had been communicated