hi OP, I haven't rtft but just in case you're still reading, have a hug.
loads of us (including myself at times) get hormonal rage and loads of us have trauma after covid.
i guess your first was a total lockdown baby and that must have been hard (my younger ds is almost 3 so it was 2nd lockdown wave but still rough!)
you're allowed to feel your feelings. your mental health is really important. DH should have your back.
one option is to lean in to how you feel, really honour your bond with baby and your rules, and make a nuclear-family-only bubble for the first few weeks and have zero visitors, zero germs (i hope!) and just a lovely extended stress-free early baby time.
tell her you'll be in touch when you're ready for baby to meet people but expect baby to be at leat a month old before meeting anyone outside the household.
this would be really valid. i have a few friends who've done this and it's your baby, your rules, your call.
personally i didn't do this, i wanted to show my babies off when they arrived and when we could we had visitors early. but like with everything, there's a million different 'right ways' to be. you do you.
MIL will have plenty of time to meet the baby when you're feeling calm and comfortable and securely bonded.