You’re clearly feeling vulnerable and getting angry to defend yourself because you feel attacked. My mum has health anxiety, I’m familiar with how it feels to be on the receiving end. So, in the nicest way:
Your babies aren’t newborns. They’re through the most risky part, they need to build their immune systems.
Flu and rsv isn’t transmitted through kissing. They’re airborne illnesses. You’ll know this when your children start school (or if you google it) and you see they’re not all kissing each other every time they come home with a viral infection.
It’s not common sense, or even sense, that kissing a child’s food risks exposure to the flu. Can you hear what you’re saying? It’s easier to believe that you hate your MIL and don’t want her around your babies, than to believe you think a human can catch the flu via their feet. Again, can you hear what you’re trying to make people believe?
Nobody is saying your postpartum anxiety is your fault. It’s nobody’s fault, and even if it were that would be irrelevant. It is your problem, which is a very different thing. Making other people work around your problems isn’t solving them. It’s shirking responsibility for them. It’s selfish, irresponsible and will ultimately backfire on you (if you really can only think about yourself). I do hope you want to solve your problems, rather than indulge and nurture them.
Whatever your brain is telling you to do: it’s your brain, in your head. You have to take responsibility for its erratic behaviour. Nobody else can or should do that for you, everyone else has their own brains in their own heads telling them their own things.
Basically, you need to take responsibility for yourself. You can’t expect the world to act irrationally in order to make you feel better, especially when you’re forcing people to behave to their own detriment and accusing them of things when they don’t. That’s not how life works. Well done on seeking help. Make sure you engage with it rather than continue to lash out in anger and blame other people for things that aren’t even happening. It’s really not fair of you and no, you don’t get a pass because it’s not your fault. Nobody does.