Guilt arises, I think, when we feel like we betrayed our duty to someone. Remember: life was imposed on you. You deserve happiness and if it's not obtainable in this life, you shouldn't be held accountable for leaving this life behind. Suffering doesn't breed character, most of the time; often, it causes even more suffering. These are obviously existential questions which you will probably never completely resolve but know that wanting an escape from pain is NOT cowardly.
If you can confront yourself directly and say to yourself that you played your hand as best you could, then why feel guilty? Sad, yes, but why the guilt?
I have come to the conclusion that I have no duty to stay alive, and besides my death will benefit others more than my continued sad existence. Luckily I had no children and leave no legacy except some money which will help those I leave behind.
Sometimes loved ones of those who completed suicide express a sense of relief that the loved ones pain is finally over.
Does your family know of your suffering? Mine does.