This is quite a complicated sitation but basically it started off when my DB was born (he's now 12 and I'm 19), my parents thought it was best my brother never knew about my biological dad, that he believed we were full siblings. I was told to call my stepdad "dad" around him, being quite young still at the time I didn't really question it and just went along with it. I slip up sometimes, DB has noticed that I call my stepdad by his name sometimes but I just do it as a joke or when I'm angry at him. But the other day I completely forgot he in the room, I don't get on well with my stepdad most the time and we were having another silly argument when I mentioned him not being my dad. This obviously confused DB, stepdad left the room and told me it was problem to deal with so I explained everything to DB. He seemed okay with it but then avoided me for days and when I tried to speak to him earlier he said "if mum and dad weren't going to tell me you could have, you didn't have to lie to me". It obviously a lot of take in for him but I don't understand why I'm getting the blame, my mum is annoyed with me too, yes I'm the one who let the truth slip out but I didn't make up the lie in the first place