Will she hurt him?

Our rescue kittens and their mamas has begun to inspect our living room. The two youngest kittens are the bravest ones and for a few nights now they visit our bed for an hour or two before they go back to the other kittens. Our cats Zasha and Izzy has accpeted this but today Izzy had enough.
Little Wesley was sleeping next to me in the bed while I was reading when Izzy came in. She came to say hello to me as normal but I could see she was upset on her body language. For a while they both lay on the bed - 3 decimeters from eachother, purring when I hold them. I could see that Izzy was tensed and suddenly she had enough. She screamed in a way that really ices your veins and lifted her paw to hit the kitten and all claws were out and ready. I stopped it by placing my hand on her neck and after a while of loving attention she calmed down. The kitten didn't move. Then Izzy walks of a bit and suddenly she turns around and scream again and attack me. I rais my hand and she stops in the middle of the attack. I pet her for a while and she seems fine but when I stop she attacks me again. I repeat my be behavior but the third time she attacks me I do the same as she does. I scream the same way (as good as I can) and I raise my hand in a more threatfull way - as she did. She runs out of the room. I go after her and I lift her up and hugh her for a while and then I let her out (they have a cat-door but it is closed for going out because of the ferals).
Do you think she would have hurt Wesley if i wasn't there?
Do I dare to leave them alone togehter on Monday when i go to work? Even if the youngest kittens are ten to eleven weeks now she could easily kill them with one bite.
Zasha always hisses at the kittens before she does anything. She only slap them if they doesn't respect her hissing and never with the claws out. By now they respect her and keep distance and she seems fine with that.
Izzy didn't warn first - she just exploded.

The question is if this was some form of jealousy - him being near you.

If yes, you perhaps dont need to worry to much.

If no - I wouldnt dare to leave them together, not now.

Can you have them separate? In a emergency one of them in a big dog crate when you are at work. Probably the kitten.
Or in the bathroom.

I think it might be jealousy but also fear. Izzy is the lowest one in the old hierarchy and I guess she is not adult enough to handle the situation.

Did I do the right thing? Is there a more appropriate way for me to react?
I will guard them them carefully during the wekend and if no solution I will find a way to separate them when no one is home.

Mybe I can take the two brave kittens with me to work. I brought two chickens once.

If they're small enough for her to hurt them, you must separate them when you're not around, no question. Make sure they all have boxes, water, treats, whatever, and then you'll be able to relax.

I will separate them when we are not around. It still puzzels me though. Later she ate head by head with the kittens in the kitchen and she sniffed them when she passed them without even hissing at them.
I am also puzzeld by the fact that the kitten was not afraid when this happend.
Later that evening both Izzy, Zasha (our grown cats) and the two tame kittens Wesley and Ice slept in our bed without a problem.

Could this be a smell-thing?
The kittens had been exploring our intire living/bedroom this day and when Izzy first came in she checked all her favorite spots and they all smelled kitten. Then she came to me just to find that both the bed and I also smelled kitten and she was all out of comfort zones of her own.
Could vanilla extract help here? If I spray both her favorite spots, Izzy and the two most explorating kittens with vanilla extract?

This is the firts time Izzy shows any kind of agression to any one. She is also born feral and grew up in a cat-rescue in one big room with loads of other cats.

Food trumps everything - and two cats who act like sworn enemies all day will suddenly be best friends in order to eat side by side! After a while nothing they do seems to make a lot of sense, but if you look at it another way, everything does!

Well, any Idea about my theory and how to deal with it in an appropriate way. Today it has been som growling but nothing physical.
Larke, If this make sense to you can you please enlighten me.

Im thinking about the smelling theory. Could be. In your version perhaps. Or he, smelling in everywhere, got on him some funny, strange smell.

There are examples of quite sudden, serious attacks with barely a warning, if the owner or fellow cat has on him say - smell from a enemy cat from outside.

One of the few occasions when an otherwise kind cat can show up real aggression.

I didnt thought about it before, as your kittens are inside / and there is fence around the house.

I think my last post was misleading, punctuation wise. I meant they'll do anything to eat, and if it means being side by side, they'll do it. Cats are definitely not easy to figure out (like dogs are), and seem to get flashes of craziness all the time, often over nothing we can figure out! Or they'll sit and stare at a wall or door making you think something's up, and nothing is, or they'll wash each other (how sweet!), but then get carried away and use it as a dominance activity and begin attacking the others... and they get their targets all mixed up - a strange cat on the lawn (seen out a window) is an excuse for attacking you or your other cats, etc. etc. etc.