How do you know if they're flirting or being friendly, don't want it to be awkward

So I got talking to this group of people and we was out drinking, so I thought I had finally made some friends. I've found it hard to make friends because I'm shy

The next day one of the people add me on facebook and start talking to me, at first I thought it was friendly, they was saying I should come out next week.

But now the other stuff they've said sounds more flirty than just friendly, and I don't see them in that way how do I get out of this situation without making things awkward losing potential friends

I'm not a 100% sure it's flirting, I don't want to of taken it the wrong way