@youhearditherefirst
She is a co-worker he has feelings for, she shot him down and he continued to txt her sporadically which she ignored - I've seen the txts!
He then txt her about our child. When she wasn't engaging he sent the picture.
No way are you even remotely being unreasonable. No way! I feel so fucking furious for you, how dare he use an innocent vulnerable child like that, to get his jollies from another woman? What sort of sick degenerate is he?!??

So your husband has admitted to having feelings for a co-worker, still works with her, and still texts her?
And you're ok with him still working there? Let alone texting her regularly?
Let alone now while your DC is ill?
What a selfish, cold, disgusting piece of garbage he is!
Sorry but him still working at the place his co-worker who he likes works, would be a deal-breaker to me, I would have demanded he change jobs.
On top of that, texting her now and then would be a deal-breaker when he is married and I know about his feelings for her.
Then, texting this her when his child is sick, and sending HER a pic of your and his child?
OP, every single one, each of these three on their own individually are LTB category. But acting like you, his wife and mother of his sick child is over-reacting that he is using your child in a vulnerable situation and an image of them to get the attention of the co-worker? While he is a married man and your child is sick?
OP, seriously, this could be more LTB territory. I could never, never forgive him for a) having such disrespect for me, his wife and mother of his child, and b) having such disrespect for our innocent child who shouldn't have their sickness exploited for him to get his jollies from attention of another woman. You didn't consent to him photographing/sending a photo of your child in such a vulnerable position. And your child sure as shit didn't. OP I could not ever come back from any of the 3 individually, but put them all together and add on the vulnerability of your innocent child he used, sorry, he would be thrown out that night. I could never get past that, not even in several lifetimes. The moment he used an innocent child to get attention outside the marriage, any like or respect for him I had would be gone. Using an innocent and vulnerable child like that is despicable and there is no justification, no excuse and no getting past that. Ever.