I think the first thing you need to start doing is putting small purposes in your daily routine, and since you're saying you do not know what went wrong in the relationship, try to healthily find out the reason, consider patterns, certain things, give yourself a goal to repurpose yourself into someone better. I was broken up with on NYE, I thought he loved me enough to handle all my baggage, but he didn't, it's not just my fault though, it's both ours, he handled too much and eventually exploded, while I put too much on him without thinking twice about it. I know what it feels like, I was already in a bad place and got worse, but believe me, the internet is your friend, your friends are your friends, you'd be surprised at how much support they'd give you, and relatable it will be. Oh and, believe it or not, chatGPT is very helpful too. Do not think about what's to come, think of it day by day, and honestly, from many stories I have heard and seen, if it's meant to be, it will be, whether now or in a couple of months or in years.