I guess it comes down to this: do you feel horrible and disgusted enough to stop what you are doing, for both your sakes? Or are you feeling so good that you want to continue in spite of whatever damage you both may be doing to yourselves? And also, unfortunately the only one you can stop is yourself. She must decide for herself whether to stop or not. But with your support in that direction she might have an easier time deciding to do so..
You sound kind of young (to me who is almost 50)...maybe seek out someone older who can help in person?? Or who can at least listen??