<human>: Give me a shortened version of the text

So I've been working for this family for about 5 months. Nicest people in the universe. I work in their home about 40 hours a week with their special needs daughter. They are often home when I am there and I've formed a pretty good relationship with them. This is my favorite, and best paying job I've ever had. 

So I am new to the area that we all live (TN) and I don't know many people. I do have a gf of two years and we plan to spend thanksgiving together because it's her birthday. Since i don't know many people, and because I'm new to the area and they are the sweetest people ever, they invited me to their thanksgiving dinner. When they first asked I kind of just froze and said maybe because I didn't know what else to say.

I need to know how to politely decline their invitation. I got asked for a second time yesterday by them and I still said I don't know yet. I feel really rude for doing this even though it will be a large crowd and it probably wouldn't be any more work or accommodating for me to come.

How do I decline without coming out, and without making up a huge lie?
<bot>: employer doesn't know I'm gay, invited me to thanksgiving with her family, I need a polite way to decline without coming out to them (not ready yet).