Tell me I’m not crazy

My mom basically let this man believe my twin and I are his kids. He turned out to be a deadbeat anyways but his family welcomed us. It makes me uncomfortable lying to them. Now I have all this fake family and a fake brother and I dont like being around them keeping up this lie. My mom gets all pissed off at me and tells me I need to be quiet but seriously? She claims that my “dads” mom knew we weren’t his but said she’d love us the same. Even if that was the case that doesn’t excuse not telling everyone else