Firstly, don't starve. You're NEVER supposed to be hungry on South Beach! You're supposed to force yourself to eat snacks even if you're NOT hungry. If you starve yourself, your body's gonna freak out and start storing fat for the famine, and then you'll NEVER lose any weight.
Just follow South Beach as closely as you can. Remember that it's different from Adkins (far healthier) and that everyone's body reacts differently. Four pounds in the first week is a good start, I think! You're not gonna lose 50 pounds overnight, ya know.
Sorry to hear about the breakup. This is a good time to take something negative that's been handed to you and turn it into a positive. The breakup is the fuel for your fire! God hands us lemons sometimes, so ya gotta make lemonade (with splenda, of course.) Not exactly Scriptural, but close enough for who it's for. Focus on that breakup and use it to make you stick to the diet!
My focus is looking at old pictures of myself when I was skinny, and then looking at what I was when I started. (I have pictures of a very unhappy Lisa in her bikini in May, if anyone is interested. "Before" pictures.) I don't like being overweight Lisa. I want to be "Proud to Wear a Bikini" Lisa, or "Holy Crap, Look at How Good I Look in My Wedding Dress" Lisa.
Everyone's got a reason they want to lose the weight. Don't make the breakup THE reason, but use it to help you along. You're doing great!!!! On which other diet can you lose 4 pounds in a week, and do it healthily? (Answer: NONE!)
Good luck!!!! And don't forget to eat!!!!