Oh Kidshappen I am so sorry this is happening. I want to give you hope though.With every stage in his fight with endocarditis(multiple open heart surgeries) and the many many complications that came DS battled it, We thought we had lost him because of the many many organs it affected but somehow we plowed through along with good doctors,lots of prayers and just taking it day by day .
DO NOT GIVE UP HOPE!Tell J's mom and DD as well,,Do not give up hope!
Did they tell you which heart valve was affected? Mitral or Aortic?The other thing many many folks do not know about is giving the patient immunity,I am sure the infectious disease dr or Immunologist who are involved in his care can advise you on putting him on IVIG(this is for primary immune deficient patients) Pre and post op. Please look into it Its a high dollar product yes but Please ask about it, Takeda makes a product called Gammagard that has been around since the mid 2000's and he might be a good candidate for it.
Since I have walked in the caregiver shoes I have a lot to say about this condition and if you would like help support or a shoulder I can PM you my phone number and be there for you, Sending prayers your way.
Wanted to add surgery might go longer than they tell you depending on how badly the valve is damaged so go prepared. Seeing J post op will be really really difficult since this is such a major operation be mentally prepared as well.(((HUGS))) (((HUGS))) (((HUGS)))