Establishing a good communication with the others matters a lot in life, especially with those who make part of the family, including siblings of course,
Decisions and steps forwards aren't that easy if you are avoidant person with psychological issues,
How the communication matters? Well, for sure having bridge of communication with them is going to reduce your anxiety and improve your mental health,
You may get a good support and help from them and this depends on how much steps you decided to get closer,
Being isolated and separated from them made you feel different from them, has influenced on you in a bad way, especially if their relationship between them is going healthy!
Keep moving forwards, and get closer as possible as u can to your relatives, take a weakness point that it used to be in past and make from it an advantage and a new start!