How to finish a campaign without our DM?

My friends and I were in a campaign together, 2+ years in the making. Due to some unfortunate personal issues, the players decided to part ways with the DM. It's been over a year since that and we would really love to give our characters a proper ending to their story that we invested so much time and love into!

Any recommendations on how to run a short campaign without a DM? We've been working together on the overall plot, but have no idea how to handle the logistics of actually running the game. There are 3 of us, and we tend to lean heavy on RP and light on combat. Thanks!

Edit: I appreciate the offers and suggestions to hire a DM, but 1) we don't have the budget for that, and 2) we prefer to play with people we know and trust, having a stranger at our table, in charge of our story is not the way we want to go

As for one of us stepping away to DM, that would be a very difficult decision to make. As I said, we each have 2+ years playing and developing these characters, to write one out and ask a player to DM is something we don't want to do unless necessary, which is why I'm asking for alternatives.