They (Bale and friend) drove back together across the border leaving the gf to bring up baby alone, and when they were over the other side Bales character confessed there was 3 grands worth of drugs in the boot. Friend got upset and Bale flipped again and put a gun to his head.
After they all calmed down they drove to the drug drop off point to meet up with the dealer who was handing over the cash. Deal is done, but then dealers brother comes out of the house and it is one of the kids who were mugged near the start of film. Gun battle ensues and all the drug barons are shoy dead. Bale and friend escape but drug barons father comes out of house with shotgun and shoots at car fatally wounding Bale
Emotional scene next where Bale begs his friend to shoot him and put him out of his misery..he shoots him..the end
BTW I hated this film, was it really necessary for everyone to talk like they were auditioning to be a guest on Jerry Springer