The fade turns into a slice when your clubface gets too open to the path. work on a way of getting the face more closed at impact and the fade will be controlled, but do it too much and it will turn into a pull. But then this is the fun of golf. Clubface control is the real skill of golf, and is very variable. Its the reason why most pro's are hitting only 60% fairways and 60% greens.
My recommendation to you is to go to the range and work with closing the face through some method of your choice (I use a closed face at address, or stronger grip, or more hand rotation). Then you have a tool to close the face more if it starts going awry on the course.
Try to think less on the course, which should give you a more consistent pattern. If the slice starts occurring, implement one of your tools in the practice swing. If that doesnt work, then do it over the ball too. If that doesnt work, then aim at the left side of the course. After your round of golf, go and work on your 'face closing tool' again until it just becomes instinct.