While on the one hand family can be a source of great comfort and strength (not to mention terrific birthday presents), it also causes all kinds of pain and sadness when family members don't live up to your expectations, or when things fall apart. That's exactly what happens in Hatchet. Brian alternates between comforting memories of his family in the past and unhappy realizations of the faults and shortcomings of his parents. He may be out there in the wilderness at home, but his parents are always present in his memories, and that both drives him and challenges his need for survival.
Brian seems to be angry with his mother for demanding the divorce, but he's really ticked off at himself. He thinks he shares his mother's guilt because he knows her secret and won't tell his dad.
Being away from his family is actually a good thing for Brian, as it allows him to come to terms with the divorce and lets him see for the first time who he is outside of the family he grew up in.