Get the proper support you need from everyone you know to help you eventually tell your dad the truth. At the end of the day what is the worst case scenario? Would your dad turn cold disown kick you out in contempt because you lied to him all this time? Or maybe initially be a possible ugly mess, mix of emotions, confused, angry, mad, disappointed with the lying but not actually disappointed with who you truly are at your core? Long version. "fit in"  Yes the feeling of being at harmony is one of the best feelings. Unfortunately life is conditional and harmony is a flawed human construct, we do what we can but wanting to loved at our worst deepest base fundamental level is what all humans want.  "Too stubborn" Stubborn is a word for not understanding ourselves at our most vulnerable level. We never been conditioned taught to truly process our emotions thoughts. I know how hard or basically impossible it is to even talk to your parent about this. Have you tried talking with all your other family about this? If they were truly supportive they wouldn't tell your dad and be ready to support you when you do. Take things at a safe pace because I had no coherent decision making, I have many regrets during my early twenties.  I would say since your case is relatively less taboo than others, you could be able to find no cost counselors or even college, school, community mentors to advise you on how to approach this. Or talk with your discord friends whatever people use. Think about the countless years of missed real bonding you can have with your dad if you could truly talk with him. If you're financially well off and eventually plan to move out, people say as a thought experiment. You spend most of your life with your parents during the first 18 years of your life. You spent the rest of your life meeting your parents for the remaining smaller portion. Rough math. Staying at your parents for a whole 24 hours weekly still makes your 62 years remaining to at least 80 about 9 years half the time you spend when you were a kid 24/7 with your parents for 18 years. 9 years spread throughout 62 years or less based on your family genetics. That 18 year 66% to 9 year 33% ratio gets closer to 90 and 10 if it isn't weekly visits. If you fear disappointment then depending on how he used disappointment, it could be weaponized disappointment. I didn't realize about the concept of weaponized disappointment until my mid twenties years after the weaponized disappointment happened. Your mind will still develop heavily in the mid and late twenties. You're still that 11 year old person, we all are. Our minds just unlock the ability to challenge think more deeply about our past and life itself. Try checking cptsd trauma and if it doesnt apply to you then keep finding other conditions. It's going to be hard to find the condition they explains your case but when you find the reason explanation that makes your heart soul feel something you never felt before that's a feeling, a sign you need  search deeper about it so it can guide you to healing. Idk but have you considered why your 11 year old mind thought you should lie? Was it to keep up the appearance of being normal in the family among friends school community etc? Based on what I think it must have come from an influence the judgement must have come from someone you interacted with before you were 11 years old. People, kids are born without filters. We slowly start filleting what we think benefits us to avoid punishment consequences pain etc. I think your 0 to 10 years, pre 11 year old mind might have been influenced by something your mind hidden deep down inside,  things are never forgotten only suppressed during childhood. Idk if you're asking me or talking about your dad. For me idk if trauma caused the stutter. My dad doesn't shame me for the stutter, that's why I think it's generational trauma as people mention.