Having to live with this lie that my husband cheated

I've been living in this lie for 9 years. I probably need to get therapy because it's caused me to resent my "son".

My husband and I legally adopted his nephew when he was a few weeks old. This is actually is nephew/brother. My husband's mom was arrested 10 years ago because it came out she got impregnated by my husband's brother who was 16 then. His mom found gay porn on his phone and she decided to turn him straight she would force him to be sexual with her and that happened for 2 years. Then she got pregnant and everything came out. She went to prison and his brother hung himself in his foster home. My husband and I agreed to take the baby. What I was not okay with was he told everyone the baby died because news like that spread like wild fire and he started telling people he had an affair and the mom dipped so this was his baby.

I understand he didn't want him growing up dealing with everyone know the was made from rape, child sexual abuse, and incest. But I just haven't liked having to live with he cheated on me. My parents hate him and because of that they don't really accept our son. They used to refer to him as the "affair" kid. He calls me Mama and I do love him before anyone starts. But having to live with being the idiot wife who stayed with her cheating husband after he had a baby on her also isn't fun. I wish we went with something different but that's what he came up with and at the time I couldn't think of any other story to tell people instead. I'm upset because at holidays my family brings up my husband's "affair" even though I ask them not to and they were so mean towards my son that I've had to cut them off and told them to come back when they can be civil.

I guess my life constantly being affected by this is causing me some resentment

@Laura we didn't think the adoption thing would work because he looks exactly like my husband's brother which means he looks a lot like my husband. We were also really young and first time parents when we went through this. We got married at 18 and 19. Had our oldest at 20 and 21 and we're both 22 when we adopted him.

@Tammy we can't because they wouldn't keep it to themselves. I know my parents and they would tell everyone. Including our son who thinks my husband is his biological dad and I'm his adoptive mom.

@Ki again we didn't think the adoption thing would work because of the resemblance. We were really young. My husband lost his 16 year old brother and had to cremate him. Then before we knew it we were taking on another child. Everything happened so fast.