Sending you lots of hugs, and reassurance that you little one will manage. It is so hard on you because it feels so good to meet his needs and it is so close and intimate, but loads of babies are brought up lovingly and happily with formula. As a pp-er said, that is what formula is for; when a medical issue prevents a mother from breastfeeding.
I am sending you, your partner, and your son lots of strength and courage to get through this, & lots of calm, healing energy.