Our answer can be influenced from a cultural perspective regarding responsibilities, relationships and how improvable is each situation, it's something I think we should keep in mind. During WWII in some european countries and Japan it is known that there were mass suicides, either because they considered defeat more disgraceful than death or because many were afraid of possible reprisals and preferred to end their lives rather than suffer that. This thought may be due to deep-rooted traditions, the harshness of the living conditions in that situation or even propaganda (as was the case with nazi propaganda). But the actual act of dying transcends cultures and our very existence, so what should matter in deciding is what you really feel is right.
Suicide is selfish? Many times yes, but it's also selfish to force someone to continue their suffering just so you don't have to deal with the grief, and it's even more selfish to do it to a stranger just to feel good about yourself. By definition, prioritizing your own interests, pleasures, and benefits over those of others to the point of stripping them of all importance is what is known as "selfish." Creating bonds is the result of living in society, not the machinations of malicious people looking for how to screw other people's feelings by killing themselves, that's why many suicidal people tend to isolate themselves, gradually cutting ties while looking for ways to minimize the impact their death may have. Then is that more selfish than using someone as an emotional crutch? Suicide is complex, not itself but the causes that turn it as the only viable option for many, so it is selfish and even foolish to reduce all this to mental instability instead of trying to understand the reasons that led to suicide.
There are those who question which pain is more lasting and intense, but it is a rather delicate subject, mourning linked to emotions such as guilt is devastating, it destroys you as a person in a vulnerable period, throwing all your mistakes at your face. I've been through it afew times, It's something I don't wish on anyone and it's one of the many reasons suicidal people try not to let anyone they love take the blame for what happened.