Ok, I'm gonna talk some sense into you. This is going to be harsh, so brace yourself.
Get the seat tube repaired.
You know you want to do it, don't kid yourself that it won't be worth the money. It'll be worth it to YOU. You've been through so much to get this bike and now you won't fix it? It's not about the money, it's about having the bike back and looking after it the way it should have been done years back when you decided not to lock it up (SHAME on you!).
If you get another identical frame, it actually won't be identical, as it won't be yours. This one is yours and it deserves better. So sort yourself out and get the frame sorted out. If it's all about the money its worth afterwards then you didn't deserve to get it back.
You got it back free anyway, how good is that???
I got my Kilauea back (see my sig for a link) and I would have done ANYTHING to restore it back to how I first had it. I would have saved up and spent whatever was needed to fix it up. Thankfully it was straight but it did need repainting and new decals. The tubing decal alone cost me £15 as I had to get it from the USA but my baby deserved it! I'm dressing it up with the best parts I can afford to say sorry for leaving it for so many years.
And I'll never sell it. You won't either, so the resale value isn't something you'll ever need to worry about.