Who is River Song to the Doctor?

OMG Melody is River Song. In the last episode I said out loud that I bet River was the baby I didn't think it was actually gonna be true. For the longest I thought she was the Doctor's wife from when we first met her with David Tennant because she always says 'my love' or 'darling' like they were lovers. Then there leaves the question why did he have her put in jail? And was she the astronaut that shot him in the season premiere? Any thoughts on the midseason finale?