1) momokocove has already stated that he will not be putting bettas with goldfish. He has clearly heard everyone's concerns about this.
2) @momoko, if you do not desire to keep your goldfish or know that you are unable to give it the proper care it needs, many LFS will take fish in and put them up for adoption. To know if you have the capabilities to keep your goldifsh in good health, you must first let us know how big the fish is right now, how big the tank it is in currently, and temperature management efforts you have tried.
Goldfish are not easy fish to care for as most people think, they produce excess waste and get very large. Lupin on this forum has very detailed information on how to properly care for goldfish. PM him if you have specific care questions. As for the information you have given us, Goldfish thrive in lower temperatures. If your tank is 80F unheated, then you should invest in a chiller if you expect and want to keep the goldfish long term. If you want to have a betta and not the goldfish, then you should call up your nearby LFS's and see if any will take your goldfish for adoption.
3) Bettas thrive in higher temps, 80F is ok for them. Goldfish are the opposite, they need lower temps. Goldfish are not tropical fish.