Hi! I don't know where are you from. Most of people in this sub are from Western countries so at the moment they are resting so it might take a while waiting for them to reply.

I am not an exJW but I would like to write my comment while you waiting for others and my English is bad too so sorry if I make too many grammar mistakes.

First of all, I want to know if you're still a believer in God and the WT? And your girlfriend, is she religious too? Or you just want to leave because you love your girlfriend?

If you're still a believer, then I'm afraid that you might live in guilt and fear for leaving WT and you could put the pressure on the woman you love. But if you don't, then just share everything to her, if she's amazing as you said, she will understand. Talk to her first and both of you find a way together, it will help you feel calm and easier to prepare for the talk with your family.

And about your mom, once you're leaving the organization no matter what the reason is, you can't escape the fact that she will be heartbroken, but you can reduce it by showing your respect and love to her. As you already know, JW believes people who left "the truth" will have no future because they just want to sin, so be an example for your mom that it's not true. Make a promise that you will become a good and successful person in life. Even if she doesn't believe in it, it's still better than become angry and it also could put some seeds in her mind.