I’m 7 months pregnant and was put in a performance improvement plan because I’m to emotional… I lead our nonprofit’s marketing team.

Firstly, sending you a giant virtual hug! Are you in the UK? The reason I ask is that i'm most familar with UK employment laws. You do not have to put up with this. Find your companies Performance Improvement policy, it should be made available to all employees. It should detail their process and typically this PIP should not have come as a suprrise, it is best practice for there to have been informal conversations prior to putting you on a PIP, if there haven't then this PIP could be considered pre-determined and procedurally unfair. Pregnancy and maternity are also a protected characteristic under the UK equality Act so your employer must tread carefully. If you are concerned about unfair treatment (and it does sound unfair given the detail of your post) then you can raise a grievance which may offer you some protection but will also highly to your HR team that PIP processes are not being followed correctly and there is potential employee discrimination happening. Also check out an amazing UK charity called Pregnant then Screwed, they have a free helpline operated by HR professional volunteers

i know we are more sensitive while pregnant, but do try to leave that at home. i was pregnant twice and yes you are more sensitive but not at work. you do not mention if you are actually sensitive. asking her if youu were gonna be let go is pointless for TWO resons , they will NEVER tell you and they know they cannot fire you because you are pregnant, they are putting themsleves in truoble if she says that. you should already know this.