Welcome to the forums and I'm really glad you decided to join us after what seems like a really long time. I hope that you'll find that being here is worth it with the community that we have.
I'm not a parent but I have no doubt you'll get lots of responses from parents who are in the same boat as yourself.
What I did want to say though was a little welcome, because I know it can be really hard to reach out for the first time. It sounds from your post like you've been working really hard on your own mental health and trying to find some consistency.
Gaming and screen time can be both a positive and a negative thing! It can be hard to find a balance in normal times let alone the weird times that we are living in now. Here's a great article on screen time that might help - https://www.esafety.gov.au/parents/big-issues/time-online
What do you think is making your child so sad at this time? Is it the feeling of not being able to play, see his friends.. ? Being able to look at the reasons can help his mood and find some great alternatives for gaming.
I hope that you can show yourself a bit of compassion during this time. It is hard for everyone and there isn't a scale of terribleness - it's okay if you're not feeling grateful and you don't need to be! It's okay to feel how you feel.
I hope that this helps a little