Even if this guy were a wonderful guy, you would probably still have a hard time adjusting to him right now. It wasn't your decision to have your parents split, and you may be thinking "Why should I have to adjust to anything?" and that can make you feel angry, bitter, or just plain confused.
Whatever you are feeling is alright. Your feelings are real, and you need an outlet for them. Have you thought about or talked with your mom about the two of you (or if you have any sisters or brothers) going to a counselor? It could help you understand and let out a lot of these emotions welling up inside of you. It could probably help your mom to understand you better, too. If she doesn't want family counseling, maybe seeing a counselor by yourself could help just as much.
Your friends could be more support than you realize right now. Is it something you are not ready to talk about and that's why you haven't told a lot of your friends? Or do you feel that they won't understand? I really encourage you to talk to a couple of your friends about what you are going through. Have any of your friend's parents gotten divorced? Even if they have not been through what you are going through, just having someone listen to you can really ease your burden of keeping this all inside.
In the meantime, why don't you write down how you are feeling in a journal. Even if you aren't sure what you are feeling or what to say, just write down the thoughts you are having. It can really help you to sort things out when you write, or when you go back later to read over what you've written.
It can look like others have it so much better than you, especially when you are having to endure something like this. But, never underestimate what people have to walk through in their own shoes. People don't always speak up about the hardships they are having, and when you are looking from the outside in, it can look perfect. But looks are deceiving, and you never know - others might be envying you and your "easy" life. Maybe some of the very people you are envying yourself! Life deals out some hard knocks to everyone, and it takes time and patience to overcome. Faith and hope help a great deal as well, so if there is anyone you find encouraging or wise, go to them.
There's help out there, but it's up to us to find it. A lot of people are willing to help wherever they can, and will feel honored by the asking. Teachers, people at a Church or Temple, other kids, people at a local youth center.... there's people all over the place waiting to listen and help.
I wish you much strength and courage (but it seems like you already have that.)