OP, I could have written this myself only a few months ago!!
Especially the part about not wanting to go out and get drunk and also the part about not thinking about your own life as you were so focused on one together.
I was absolutely devastated..we lived together and had been together for 3 years. I was 25.5 when it ended. I thought I would be alone forever and cried and wanted him back. But a strange thing happened...after about a month, I woke up one day and suddenly realised that if I tried to get back with my ex, and it worked, would I be happy? Properly happy? I realised that I wouldn't. And if I got back with him, then the risk of having that life I wanted - companionship, sharing a life etc would be even more unlikely to happen. That's because my ex, like yours, wasnt giving me the security and companionship I needed. So, in actual fact, it's MORE risky that you will end up alone if you try and stay with your ex.... if that makes sense? This is what pulled me through. I looked at the relationships around me that reflected what I wanted in someone...security, a base and a future, and decided i deserved that, too. And my ex was no demon...he just didnt want those thigns and I did/do.
So, 3 weeks after coming to this realisation, I've met somone absolutely lovely and amazing. It might not last, and funnily enough, I am ok with that as I am ok with waiting until the right one comes along. But if it does last...well then I'm going to be all the more glad I ended something with someone who couldnt give me what I needed in a relationship.
For what it's worth, security and companionship and sharing a future are NOT big asks. You will find this in someone else quickly, once you're ready to date again.
I know it's shit now, but imagine wasting another 2 years on him and being even more alone and missing out on that someone who WILL be around the corner, I promise you that.
Oh, and just as an aside, I dont know how old your ex was, but I would date older guys in their early thirties..you sound like you are ready to settle down, and from my experience men in their thirties are generally a lot more at that point than those in their twenties!
Good luck :)