I know what you're feeling right now. Hell, I'm also on the same boat, been friends since college and just fell out one moment, sometime still hanging out but it feels like they just hang out with me since I have car and I'm just a free Uber.
Some bridges needs to be burned but for now try to talk to your friend, know the reason. If the answer is no good and need someone to vent out the internet is pretty big and someone will listen.
Loneliness can be a pain, it's a void that's hard to fill sometimes. Bonds that was created longer is harder to let go but that is part of changing and growing. Hell, I've been trying to reconnect to some all in vain.
So whatever happens keep on pushing forward, if they're willing to break that friendship show them what they lost.
As what my dad told me in his words "It's the moment where your balls are getting twisted and pinched is where you will know who your real friends are. Either they share the pain with you or they watch and laugh or run away to save themselves."