Use External Hdd for time machine and bootcamp

Not sure if this is the right place to post this, please tell me where to post if this is wrong.

I have an external 2 TB western digital hard drive and want to be able to use it for both backups and saving files through OSX and Windows 8.1. I dual boot windows using bootcamp. I have partitioned the external drive to 500 gigs for time machine backups and the rest for random storage, such as music. The time machine partition is in the format Mac OS Extended (Journaled) and the rest is ExFAT. I want to be able to read/write to the ExFAT partition while booted into both OSX and Windows 8.1 but i can not open it in windows. i am assuming this is because it is trying to read all of the external hard drive and the timemachine partition is not compatible with windows. Is there any way to be able to use just the one partition for both operating systems??

No, not possible since Time Machine will only work with HFS+. What you need is a driver installed to Windows 8.1 that can read and write to HFS+. I believe Paragon Software has such a driver. Go to their site and find HFS+ for Windows: LINK ($19.95)

Member chscag is right. That's the best option for your goals.

There is a procedure which allows formatting a drive as part HFS+ (Mac) and part NTFS (Windows). Last time I checked it was a bit of a pain to get set up. Even so, not sure I'd trust backup data to such a drive.