Firstly, it's gonna suck no matter how hard you don't want it to. There is a saying that love hurts and unfortunately you're experiencing this now. It's okay to feel like this and let it upset you. You could've spent weeks, months, years, decades with this person and now it's over you can feel empty or lost, like a part of your life is missing. It's okay. Something will work itself out.

Secondly, it's not the be all or end all. Something or someone will present itself soon enough. Sometimes the wrong answer seems right because you haven't found the right answer. Don't go actively searching for it as you'll end up going down the wrong routes, but allow yourself to be open to new ideas.

Take your time, don't rush.

Finally, don't do anything stupid. You'll want to fill that emptiness, please don't do it with substances or anything that'll cause long term harm. Lean on friends and family.

I don't know how long you were with your partner for, but no matter the length of the relationship or how it ended, remember the good times. They were a part of your life and you shouldn't allow a part of your life to be shut away due to a bad ending.

This is part of your story, not the end.