What you are feeling is deep and abiding grief. You have not only lost your girlfriend, you have lost the life you thought you would have. There is no shame in grieving this very much like one would grieve a death. A six-year relationship where you loved deeply is worth grieving, regardless of what your ex has to say about it. Please give yourself patience and time to honor your loss and figure out what the next chapter of your life will look like. If you are unhappy where you are, think about how to go back home. I hope there are friends there who will embrace you.
If you can’t function in your daily life after a few weeks, please consider seeking out a grief counselor or a person of faith to help give you some direction. If there isn’t such a person, please do consider one of the online communities. People who are sharing somewhat the same experience are often the most understanding and the most helpful.
I’m very sorry for your loss.
I wish you well.