Girl Help needed please-is it wrong?

I've been seeing this girl who is 15 (16 in December), and I am 17(18 in January). I feel really bad because of the age gap, does it seem wrong? Obviously I wouldn't think about any sort of sexual relations since she is still under the legal age (live in the uk). However I'm worried about how to go about it. How do we tell her family, and will this probably have an effect on our friends etc.? Would it be better to break it all off? But I don't want to hurt her, or make it seem like I've just used her. (Probably should mention that she has had problem with older boys in the past, so her mother won't be too accepting.)

Especially when you're a teenager, the success of a relationship is determined by influences and factors that have nothing to do with the two people who are involved in the relationship. If your relationship could cause you legal problems based on local laws, and her mother is antagonistic to the relationship, then you need to protect yourself and your freedom and end it.

Anytime you're involved in something you feel like you need to hide, then that's a signal that you don't need to do that thing.