I went through the exact same thing. I was in a long distance relationship for two years, and we spoke every day. He was my best friend and my go-to guy for everything. We broke up and stopped speaking altogether, giving me no time to get used to not speaking to him. I relied on my friends a lot, spent a lot of time distracting myself with work and things like puzzles and crosswords to keep my hands and mind busy, and allowed myself a little time each day to be sad or cry or look at pictures of us or whatever, but made sure I kept all that within the 15 minutes, 30 minutes, or however long I allotted. It took me months, and I know I’m still not totally over him, but it will get easier, eventually.