Had to happen. It was the ONLY way to get Gus.
Yes, it was extreme, but if someone threatened to kill not only me but my family, including my infant daughter...extreme is exactly where I'd be.
Also, Jesse owed Walt for saving his life. Say what you will, Walt would have had it made had he just sat back and let Jesse die.
More money coming in than he could spend which would have set his family up for life not to mention a MUCH more capable, knowledgeable, and skilled lab assistant in Gale who was fired to make room for Jesse, so that Jesse would not ruin Hank's life.
Some friend Jesse is.