Re: how do you cope?
First thing you need to do is get to a psychiatrist. I used to have the anger and depression swings and I was out of control until I got to a doc that I found and trusted. You need to have them help you and be willing to accept the help.
You will probably be put on meds and they may not seem to work at first, give it a month, it takes 2 weeks for the medicine to get into your system and then give it the extra 2 weeks to see how things go for you. It took me a lot of years to get on the right meds, but I finally am. I still get angry at things, I still want to hurt myself at times, but it is a lot more controlled than it used to be.
Just make sure, to keep yourself safe you also have a net. Which means you have people to call to talk to that will listen and not judge you (that's the hardest part, the not judging). You need support when you get like that, so talk to friends and family, see who you can count on.
I wish you the best.