Which Camera lens would be better?

I'm sorry I'm an amateur so I know I'll probably sound dumb asking this. I've been trying to research this but I'm still a bit confused so I would appreciate help.

I have the Nikon J1 and I wanted to buy a new lens for it. I have the 10-30mm f/3.5-5.6 and the 30-110mm f/3.8-5.6. I wanted to get the 10mm f/2.8 lens because it was compact and a wide angle but then I saw they had a new lens the 18.5mm f/1.8. At first I thought it wouldn't be worth it because I have the 10-30mm but then I saw that it had a faster f-stop. So after researching the 18.5 I found it was really meant for portraits which I was looking for something I could use more for nature and street photos as well as quick snapshots. So I think I'm going to get the 10mm but I just want to make sure I'm making the right choice before I buy it because it's a lot of money for me and I don't want to buy something I don't need.

The 10mm is $249 and the 18.5 is $189 btw.

Added (1). Which one would be better for taking pictures of stars and the moon?

You will have to visit a proper camera shop and try the different lenses to know which is best for you.

There's no way for us to know which lens is best for YOU.

The 18.5mm lens is going to be closer to a normal lens (49.95mm), and is equivalent to a 50mm DSLR lens. The 10mm is more equivalent to a 27mm wide angle lens.

I would buy the 18.5mm lens over the 10mm lens if you want it for street photos; and you will appreciate the fast f/1.8 lens. The difference between the 10mm f/2.8 and 10-30mm f/3.5~5.6 at 10mm is not a lot; less than one f/stop, while the f/1.8 vs f/3.5 is two full stops in difference.

I'm thinking you would hardly ever use the 10mm lens given you have a 10-30mm lens.