
New hobbies. Hanging out with friends or family. Journal your thoughts or daily activities - what went well, what didn’t. You just need mental distractions/stimulations. Drugs and other people are generally only going to worsen how you feel about yourself, and the relationship you’re coming out of.
For me it took four long excruciating months of crying every night and distracting myself. Eventually it stops making you sad and you just live with it. Do everything you wanted to do with him, with your friends or family. Make a big change in your life (I bought a car and moved). Go to the gym. Give yourself grace and spend time alone to become who you need to be.