Beliefs about conversations with bosses

Growing up I learned that employees shouldn’t point out to their boss things they are doing that are frustrating. Right now, because of this belief, a lot of frustration towards my boss has built up. I’m frustrated that my boss has not done the things he said he was going to do multiple times, uses ‘they have been too busy’ as an excuse multiple times, and has forgotten things that have been mentioned multiple times before.

Is there another belief about conversations with bosses? Biting my tongue is really exhausting and not serving me. I had a not-so-pretty meeting with my boss. I told him why I was frustrated and in return I was told ‘everyone has been too busy’ and ‘I didn’t know I brought this topic up three times already. I’ve even asked for an estimated time to completion on tasks he said he’ll do but I always get the same response ‘ I don’t know how long it’ll take’ or ‘Everyone’s really busy right now’. I’d really like to know why my boss keeps doing these things. He expects me not to forget things, but its ok that he forgets things constantly!

In the not-so-pretty meeting, I tried to calm myself down a bit and focus on what my boss was trying to tell me, but I slipped into ‘freeze’ mode and I honestly don’t know what else my boss said. I didn’t feel safe anymore. I ended the meeting, and told him that I needed to cool off. How can I prevent myself from slipping into ‘freeze’ mode next time?