Partner and I can’t communicate about the hard stuff because of our mental illnesses

So...I’m generally an easy going person. My partner unfortunately, I think is very uptight. Also unfortunately, we both have severe mental health issues. She has bpd/bipolar/we’re not exactly sure, and I have depression/anxiety/a general non caring-ness because of the meds I’m on.

But we have the hardest time talking about our issues. Because of her bpd, she goes 0 to 100 real quick. She starts yelling even if it’s something small. She is also an empath which makes all of her feelings 100 times more strong.
Me on the other hand, like to avoid conflict at all possible costs. Partially due to my upbringing and never dealing with conflict in my family, and partially due to my meds making me very apathetic. So I can’t handle anything when I feel like she’s attacking me.

Now I know this definitely doesn’t sound like a match made in heaven so please keep the “break up” comments away. We also live together so we need to know how to coexist and have these hard types of conversations no matter what.

Our problem is that when she feels there’s an issue, she brings it to me every time. But with her bpd, she says she doesn’t have control over her tone or inflections. And because of my issues, I think that every time she brings up a problem, she’s coming at me (mostly because she doesn’t know how to stay calm during these times). I say - I’m able to have the conversations with you if you can stay calm the whole time (which is not possible for her) so I don’t feel like you’re attacking me. She says - if you just keep in mind that I can’t control my tone and we have the conversation anyway, all of my anxiety will go away and I can be calm.

Unfortunately both cannot happen at the same time. I need her to be calm for me to hear what she’s saying instead of the yelling, but she yells because I “don’t listen” because all I can hear is the yelling and I shut down. I can’t open up if I feel like she’s attacking me, so then she just gets more mad that I’m running away from and not dealing with our problems.

Any *helpful* advice? Hopefully this all makes sense. Thanks so much in advance.