Sorry to hear your struggling so much with all this, I have been through quite a lot of therapy for many things, not just bereavement, one of the strange things with therapy or counselling, you have to do what works for you, there are different types of therapy, & sometimes it helps if you have a therapist or councilor who you connect well with, like in all professions, there are good ones & not so good ones. It helps to be clear on what exactly you want from the therapy, what do you want to accomplish from it. I know a lot of them do 6 sessions, which isn’t always enough when there is a lot to unpack, emotionally speaking.
The negative criticism thing, I understand this is a learned habit from someone else, I’ll admit with the way my dad has been constantly criticising me & berating me, especially this year, I have a similar problem, I think it upsets me more when I feel possitive & enthusiastic about something one minute, then from nowhere BAM! He’s in my head & criticising, my brain flips into panic mode, I feel hot anger, & at the same time scared & want to cry, I hear the bad thoughts as clear as if he was in the room with me, when I do manage to fight my way out of my negative headspace, I’m usually in tears, & just feel I need to get out. This is something I’m trying to work through, but I find walking helpful, & using distraction techniques like the alphabet game, especially if you go through the alphabet backwards, it’s just trying to focus on something else. But I know what you mean about self criticism being caused by years of someone else doing the criticizing, knowing why the person was the way they were helps in understanding, but doesn’t fix the pain & distress it puts us through. My stubborn angry side says they have no right to control me, they have no right to upset me like this! But I know it’s hard to feel that strong when you feel vulnerable. When the bad thoughts are there, remember it’s your choice how you choose to handle it, a thing I used before in therapy in “thought buses”, imagine you’re at a bus stop, & as buses pass they signs on the front of them which say your thoughts, they can be anything you like, from “It’s sunny today”, “I am really dreading the dentist appointment,” “I need to focus on…” but if there’s a negative thought bus, do you really want to get on it? Definitely not, if you find yourself on the negative/bad thout bus, tell yourself “off the bus!” Usually you need to repeat it a few times, If it’s not working, use an alternative distraction technique, but it tends to be trial & error finding what works for you.
Hope this helps.