Several solutions

In my experience it is easier to do harm than to do good. The body tends to like routine. I have had bad results when I have done something like a prolonged fast and then had to jump back into an un healthy Diet and an unsupportive environment.

One easy solution is to take psyllium shakes for a day or two at the beginning and end of the juice fast. It helps to keep things moving. I don't use bentonite. Just psyllium and water. But make sure its a shake and not just stirring it with a spoon. That will have the opposite effect.

Here is a metaphor: if your body is like a glass of dirty water then what is the best way to clean it? If you answered: dump the water out and refill then you are wrong. It is to put it under running water and slowly let the water become cleaner.

Also, the longer the fast and the less bowel movements during the fast, the longer it takes before your body returns to normal. It is very important to also get back to your normal diet gradually. I personally don't like enemas and think they are unnatural and unnecessary and many people agree. I strongly prefer to add a little psyllium to my fast. Or just make sure that you ate plenty of fiber for the week or two before the juice fast.

I would focus first on deciding what your priorities are. If you want to keep the boyfriend then you should just try to keep healthy food in the house as step one. If that succeeds after 6 months then you have created a place that you feel safe to fast in. Otherwise I would just focus on eating as healthy as possible.

I find that I do best by just cleansing. It usually brings better results for me than fasting. you can cleanse just by eating FRESH WHOLE GRAINS, or eating raw foods only for a few days (100% raw can be very risky).

But as long as you are juice fasting you are fine as long as you aren't Water Fasting which should be done with precautions.

Also keep in mind that if you are under 30 years old and a healthy weight then it is more important to eat healthy. I know lots of people that have messed up their health by eating 100% raw or Water Fasting when they were basically healthy to begin with.

Do consider doing Liver Cleansing herbs though. Everyone has a toxic liver to a small degree. But take stone dissolvers, don't do the flush, too extreme for me (I am only 28 years old).