Overwhelm of emotions in feedback meeting and bursting into tears

How do I deal with anxiety, mind freeze and not being able to speak up at meetings? I work hard at pushing through uncomfortable feelings brought on by me not wanting to be judged and the thought that I can’t articulate my ideas well and that they if I do people will think I’m stupid. This was compounded when feedback was given 3 months at a new company where one manager fed back to my boss that I was too quiet and should be coming up with ideas in meetings. I took this on board and spoke up more. I asked questions on email and he then reported back to my boss that I’m not copy very well. When she raised it with me I felt a rush of shame of incompetency and burst in to tears. She was supportive but I don’t want her to think I’m flakey. I can’t exactly do the model in front of her so how do I deal with this.