Be honest with her.

You can't have a real relationship with her while trying to exclude her child. They are a combination, and it isn't fair to her or her child to have to try and have a separate life for your convenience. It's been a year and you still barely even spend time hanging out with the child? You should have some sort of connection and relationship with the child now.

It's totally understandable that you're not ready to take on the role of a parent. But you really shouldn't keep stringing her along, because you can't have her be two people at once. She deserves the chance to find happiness without having someone who resents her child.