After reading your post and all your comments, I feel like your first step before making any other changes in your life is that something has to give with respect to the situation with your sibling, since it seems like you can't move forward with taking any big step without sorting out your situation as a caretaker. For example, can you somehow get the people who are supporting you right now to take care of your sibling while you can't take care of your sibling due to school/work?

I'm sure you've been trying to come up with a solution regarding your situation with the sibling for a long time, and it must be a very difficult situation with no easy solution, but my opinion is that there has to be some kind of ultimatum so that you can go forward with your life as well.

I'm really careful as I write this as I don't know what your sibling is going through, and I don't mean a single bit of disrespect to your sibling, but is it possible that they won't commit suicide even if you aren't around to help? When faced with the prospect of destitution due to you no longer being available to provide 100% of your sibling's care, do you think there's a chance that your sibling would finally change and decide to take steps to gradually become independent? Since only you know what your sibling is like, you can disregard my comment if it's probable that your sibling will kill self when forced with no longer being able to continue their current shut-in lifestyle.