My sister was widowed when her daughters were very young, so she's a single parent. I can tell you she had some very difficult times with those girls when they were teenagers. They said and did some dreadful things. But she always maintains that you have to have boundaries which you refuse to cross. You do have control over money and can withold it if you feel it to be warranted. If you maintain a toughness which can't be eroded, the youngsters, who are actually still only 'kids', will be held in check somewhat. My sister made the mistake of spoiling the girls materially with expensive presents, partly to compensate for their lack of a father. But apart from that, they've finally calmed down, are both at University and doing well. But it can be a very rough ride. Most of these difficult youngsters eventually settle down.