I'm going to repeat SoCaled advice to check the frame and look at the tubes that attach to the head tube for any bulging from the incedent. If the frame is good and the only damage is to the fork, a bike co-op is the best bet. A lot of trikes have 24" wheels. You might want to either remove the fork to match it up at the bike co-op or, if you can, bring the whole trike there. Those forks can also be bent back enough to ride it to a co-op. There is some concern that the fork isn't as strong after getting bent it twice.

If it were mine, I would use a unicrown fork on it. It changes the geometry of the trike because it is a little taller, but the fork is stronger than the type that you have and the unicrown forks might be more available. You might also have to change your brake to a cantilever or linear pull brake caliper. This would also be worth it, in my opinion. You will have a better trike after this.

I know this trike is not from when Columbia was at it's peak, but if a used fork from a co-op could get it running again. Then great. You might even find a better trike at the co-op, or this can give you time to keep your eye out for something better.

As SoCaled mentioned, if you let us know were you live we could direct you to a local co-op. Hopefully there is something close to you.