What mental troubles did Forge have, and why didn't he go with the X-Men?

Question

In Astonishing X-Men #29 (part of the "Ghost Box" story arc), the X-Men go to see Forge when they discover he was creating new mutants by adding a third chromosome to people's genomes. On the way, Cyclops says:

"...Forge is a man with a mutant genius for engineering who's also had one or two mental problems in the past. Even with his head on straight, he's never made the best choices in the world."

Additionally, they mention how poorly he treated Storm.

The events of the "Ghost Box" story arc do not go well for Forge:

He chooses to stay instead of escape with the X-Men as Abigail fires a 2-terawatt quantum laser into the ghost box in his base, presumably killing him.

What mental issues has he had, and do they justify his actions here?

Answer 1

As far as i know his mental problems started during the Vietnam War. Driven by the grief of his comrades dying in an attack, he used the spirits of his nine dead comrades to summon demons to take revenge on the enemy troops. This also caused a demon known as The Adversary to come to Earth who he went on to have many battles with.

Years later he eventually banished The Adversary forever by casting a spell that needed the sacrifice of nine willing lives, as nine were used without permission in the original enchantment in Vietnam. The X-Men volunteered and so Forge cast the spell banishing The Adversary and also killing the X-Men. They were actually saved by the goddess Roma, but Forge didn't know this and so thought he had caused the death of the X-Men, including his lover Storm. Thus the guilt of these actions added to his already troubled mind.

All of this can be found in Uncanny X-Men 225 - 227 which is the X-Men strand of 'The Fall of the Mutants' storylines.

Also in reference to his poor treatment of Storm. He created a neutraliser which removes mutant powers. Against his will this was used on Storm removing her powers for a period

Answer 2

Based on the information from the marvel Wiki Forge reached his final mental state from a variety of things. The most recent to the Ghost box story line was being betrayed by Bishop as he sought to kill the first new-born mutant after M-day. The greater underlying problem looks like it started for him during the Vietnam War(this part is not fully fleshed out in the article).

As for the second part of your question do they justify his actions I would say his during his final decline he was attempting to fix a problem through technology that could only be fixed by nature. So in his own mind he felt the end result(creating new mutants) justified whatever means it took him to get there(forcing a third helix on to unwilling participants DNA).