well, according to steams page:
OS: Windows 7 SP1, Windows 8.1, Windows 10 (64-bit versions only)
Processor: Intel Core i5-2400S @ 2.5 GHz or AMD FX-4320 @ 4 GHz or equivalent
Memory: 6 GB RAM
Graphics: NVIDIA GeForce GTX660 / AMD R9 270X (2GB VRAM with Shader Model 5.0 or better)
Storage: 50 GB available space
Sound Card: DirectX-compatible using the latest drivers
your 260x is a lower end card than the 270x. not by much though, so at least it runs.
something to remember is that "minimum requirements" sometimes means "it will probably at least not crash on this hardware if you turn all the settings all the way down" or at least the lowest end equipment they've tested it on.
so unfortunately your first step is to turn down all the settings. a lot. once its playable, see how high you can get it and maintain those fps. see if thats still an experience you want to pay for. you can probably expect some performance improvements by the time its at retail with the driver updates, but not significant ones. they will not make 10-20 fps get above 30.
you would be well served by a new gpu though, if its in your budget. an upgrade now will serve you better with everything you play going foreward. the recommended gpu is a 1060/970 or an r9 390/rx 480.