Yes, I do think that they'll break up because Amy probably can't handle something this big, and Ben would probably lose all of his chances with Amy because of the baby. When Amy first broke up with Ben it was because of his immaturity, jelously and cheating. The same might happen to them even if she doesn't break up with him right away. Amy might not cheat, but she might become jelous of the time that Ben will spend with Adrian, she may even become a little immature too.
Yes, because it will break her heart. She has John with Ricky so she knows that the bond Adrian and Ben will have will be a lifelong one now and I don't think she wants to have to deal with the way she feels when they are around each other for a lifetime.