Howling:Theory on River Song

I have been speculating alot on what River Song's role will be later in the series. From what occurred in The Big Bang, I believe the doctor will fall in love with River. Now, as to her dark past. I have been thinking for much time, who is the great man that River Song killed. She did have a bit of a surprised reaction as to seeing The Doctor at the library while he was traveling with Donna Noble. Based on her behavior, i am going to assume that River Song, will, kill, The Doctor. As she mentioned, he is going to be rather cold towards her when SHE first meets the doctor. Maybe she will cause a regeneration or she will be the complete end of him. Who knows. Please tell me what you think.