My husband isn’t invited to my son’s wedding. What to do?

My son is 26 and getting married next year.
I left his father 7 years ago (the breakdown in relationship had started 2 years before I physically left due to emotional abuse and controlling/jealous behaviour), and i started a relationship within 4 months of leaving him with someone my ex-husband knew. That relationship turned into marriage (with a 5 yr old son between us), as my DH is an amazing man who was always respectful of my son and his bio-dad. My adult son’s father suffers depression and has apparently never got over me leaving him, or my new relationship.

My son has said my husband is not invited to the wedding, me and my son (his half brother) are, my DH isn’t invited due to family drama and history. I reluctantly accepted this decision in so far as my husband will not attend the wedding ceremony, reception or evening party. However, because i want to share some part of this special day with my DH, i told my son after the evening party my husband would meet me in my hotel room so i could show him photos, talk about the fantastic day and share my happiness with him, even for just a few hours. My son said NO. He does not want him there in case his dad see’s him as the hotel rooms are on the same floor. So i said ok, we’ll stay at a nearby hotel and no one will see him. My son also said NO! As its his day and he doesn’t want my DH to have any part of it however small. Against my own judgment i said ok, i’ll go home after the evening party as I really want to be with my DH for the remainder of the day, and Son said if i loved him i would not need to see my DH at all and can do without him for one night. Of course i said I can’t and don’t want to do that as I’ve already agreed to the hurtful request of him not even attending the wedding day events. And son has said im not invited to the wedding at all if i don’t agree to his ‘only request’. So it’s either I don’t see my DH at all until the next afternoon, or i’m not allowed at the wedding.

***let me add something which i waited until the end for as it’s a messy part and i didn’t want to bias anyone reading. My DH is my ex-husbands close cousin. Please try not to judge as no one knows the details of any one else’s marriage, he is a good man and you can’t help who you fall in love with. It’s very messy, but the advice im looking for is because i’ve tried compromise and my son (who i’m close to) is having none of it.
Help please!