I know this might not sound nice, but for him to commit suicide and constantly ring your girlfriend and then leave a message like that is really selfish. Clearly if he really liked your girlfriend he would of realised the damage he would do to her.

It's not your girlfriend fault thats what i'd tell her because he's in control of his own actions. If she had gone and met with him it may not have stopped him from doing something later. Clearly he must have been really down to do something like and losing a friend or relative can really get you down.

There isn't really and quick fix for this but as said times a healer.

Hope things get better for you two mate