Another "in between" option might be for you and your boyfriend to make a sex tape with the understanding that your husband will watch it later. Of course, that also requires consent from the boyfriend (duh), but it might be easier if he has anxieties about having sex "in front" of someone.
Of course, if he's simply not ok with someone else watching him have sex either on tape or in person, then it's all off the table entirely. That goes without saying, but I'm saying it anyway because I'm learning that obvious things are not obvious to everyone...
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker