Keep in mind, people change over time. You are not the same person you were when you were 5 or even 15.
This may mean letting go of people who are dragging you down, even if you have known them for 15 years. This can be difficult, but if every time you call them they leave you feeling bad about yourself or that going off to post secondary has somehow hurt them, then they are not a friend you need to keep in contact with.
Again, this may change with time, but right now you are doing what you want to do and what you feel is important, and their fear of change should not hold you back.
Step away from that friendship and work on building the new ones or the ones with friends who are supportive of you