Based on your writing, you are totally qualified to help your aunt learn beginner-level English, or higher.
And as you are also able to communicate in her own language, it is much easier for you to explain things to her than it would be for me to do it. Imagine how hard it is to understand the difference between I sit, I am sitting, I have been sitting, I will be sitting, I will have been sitting, and all the rest of it, if you don't understand the language I am using to explain to you.
People need a good basic understanding before they can work only in the language they are learning, at least if they're using traditional methods.
Having said that, there are a couple of options for you:
- Someone (you?!?!) can create a study plan which includes some structured practise with a native-speaker. It can't be "free talk" as the goal is to activate whatever was learned in the class with you. So, one class with you learning about the past simple tense, and one class with a native-speaker practising the past simple tense.
- An old friend of mine teaches Chinese and English using a kind of total immersion, with a highly-structured program that mimics the way babies learn. You start with basic words and actions, and learn to build sentences, without ever using your own language. It's very difficult to do it well, but she seems pretty good at it. Check out http://www.terrywaltz.com/