I'm so sorry for your excruciating loss.

Take things one day at a time. Make sure to do basic things daily whenever possible, like take a walk, cook meals, do chores, read the newspaper, go for a swim, read a book, help someone out. Try to find people in person to speak with, such as a therapist.

When you are ready, look at the plans you previously had, before you met this guy. Consider to what extent those plans still suit you, and modify them as needed.