you can t fall out of love. By the sounds of it you both feel the same way so keep on fighting and going with your gut feeling. 

obviously there is a reason why you seperated which plays a big part on why you cant decide whether to get back together??

you just need to decide which one is the right one for you then stick to it. If not then move on and stay just friends with both of them.

a partner that calls you names and puts you down has no respect for you. Maybe they have issues of their own and take things out on you by doing the name calling but they also need to appreciate you as well and not be so rude and nasty to you.

there is obviously a reason why her grades would be down but dumping your child over a matter like this is definately not the answer.

unfortunately until you are 16 years of age and living under the same roof as your mum there are rules you need to abide by. Explain that you need your own privacy to her in a grown up and calm approach.