What advice could you give a brother-in-law that is miserable?

My BIL is book/computer/paper smart but a real life idiot. You see he had been alone for a while and he got with this much younger girl. Sort of a spoiled brat/street-kid wannabe. He was having a long-distance fling with her until someone better came along. In fact, Christmas, 2006 he was going to dump her. In January, 2007 she comes to him and says she is over 7 months pregnant and of course she didn't know (yeah right). He moves her in to the place he is renting and then buys a new house. Baby is born in March and it's a happily-ever-after right. WRONG!!! See he is a good dad and we all love the baby, though none of us are sure it's his as the timing is peculiar. Nonetheless, the man is miserable. She treats him like a trash can/personal bank account. No one has seen him smile for forever, all the man does now is *itch and complain about how evil the girl is and we believe him because she is horrible and posessive of him . How do you say to get the "f" outta there? Or do you???