My boyfriend broke up with me on the first day of lockdown too, I'd been with him for 5 years and he gave me no explanation. I was the same as you, absolutely heartbroken and didn't think I would ever get through it. It's only been 2 weeks now, and I feel like a new person. I know it doesn't seem like it, but I promise you it will get better. Take care of yourself, try to do things to take your mind off of it. You clearly deserve so much better than that, and things like this often happen so that better things can fall in to place. Trust in the magic of new beginnings! I promise you you'll come out the other end a much stronger and happier person.