i hate not having a set friend group

I used to be apart of a decent sized friend group that stuck together. i'd always have someone to work with, someone to sit with, or someone to hangout with but after i realized the toxicity within the group and decided to leave for the betterment of my mental health i dont have anyone i can rely on to keep me from being alone. i always worry when we have to split into groups as i dont have someone i know will work with me. i sit alone at lunch and while yes i enjoy the peace and quiet but i feel alone. i have friends but they have other friends that theyre closer with so im always left out and im always the last choice. gods i hate this.