Hello,
Im sorry you are having to deal with this. When family members are not getting along, it can be very stressful. What I think would be helpful for the moment is to focus your energy elsewhere. Try hanging out with friends or joining a club at school just to get your mind off of the situation and get you out of the house.
Also, talking to someone about your feelings can really help! I know it can be difficult to open up to someone, but just having someone there to listen can make all the difference. Talking to your mom might also help. She may be able to shed some light on the situation so you know what to expect. Just because she has been through a divorce before doesn't mean it will head that way again.
I hope this helped at least a little.
Feel free to
PM me if you need someone to talk to.