I am also a born in 4th gen close to 50. Stay away from the meetings, you have been programmed to return. Things will be said that will only heighten your imposed guilt and open you to their control. I understand your concern for your father, but you also mentioned a sister. One of the big traps is there is always someone who will be upset with you for not behaving the way they want you to. You can't please all of the people all of the time. As any witness understands those who don't love truth will fight against you.
You sound like someone who values truth. Does you father value truth and instill that love in you? Honor him by remaining a person of integrity. You don't have to hit them with everything you have learned or every decision you make. This is sadly another programing tool to control us. As they themselves bring out, they do not tell a new study everything at once but they do it when they are ready. So follow this example and only say what will be beneficial for them. This is something I do. There is a site called Borean Pickets they discuss recent meetings and point out inconsistencies. I also follow any new announcements on this site. I then proactively slip this into conversations and use terminology that makes JW's feel safe. Example: "It's just like they said in morning worship the other day... You know what was brought out in the convention this summer... " I made a point that I am having trouble getting out right now but this is giving me the opportunity for 'deepening' my personal study with an interlinear and looking at the Hebrew and Greek. Go on and on about words and definitions. Guess what, most witnesses are not scholars so they will just tune you out. I did in depth research on the words translated as sin.and shared it with everyone, they just smile and nod. But the best advice I can give is keep proving to yourself this is not the truth. Look up everything and keep records so that you can look back and see what you have accomplished. I have several folders and periodically opening them and just scanning them strengthens my resolve.