I think that approaching sister#1 and telling her what you've done and why you feel the way you feel is a good idea Something you could also do is lay down some ground rules with your sisters especially sister#1 so that a similar situations do not happen in the future. At the end of the day you are now all adults and you need to find a way to change how you relate and behave towards each other to reflect that. It can be easy to fall back into old sometimes less than mature behaviours when it comes to siblings because that's the way you have interacted for a large part of your lives, perhaps just remind your sisters of this and your need to focus on building a new dynamic. Good luck