I failed a suicide attempt in the past and am terrified the depression will return. How do I prevent it?

Ongoing treatment... Keep working closely & openly with ur therapist & psychiatrist. Early detection of worsening mood is key. +talk to ur therapist about this "terrified" feeling; relaxation training will prove helpful. + let ur commitment be first & foremost to ur healing journey. If depression returns, use it as an indicator about where u're at & what to work on next to move to the next level in the healing journey.
Sx awareness. You're right to worry. Work with your therapist and psychiatrist on sx awareness and monitoring as well as triggers for your depression. Work on a plan of action now for the time when crisis does return -- help you be better prepared. Focus on the things that work for you right now and embrace the positive experiences around you, however small they might seem.
Wise to worry. Past depression, especially with a suicide attempt, certainly places you at increased risk for another episode of depression. Not knowing how old you are makes it hard to tell you what kind of support system to set up, but that's what you need. Consider counseling to help you identify early warning signs of depression and ways to deal with it.
HOW TO. Depressions can return. If you were concerned about another chronic illness, you would find a doctor and follow your status as long as there was cause for concern, and you would take meds and do proceedures as needed. Same thing here. Ongoing relationship with your doctor and checking in periodically until the illness is gone.
You R wright. 1-yes depression can return, but luckily there are a lot of treatment for it, ( medications, therapy and ect.) 2-if u r compliant with u medications and refrain from illicit drug use , exercise and continue in therapy it is less likely to return. 3-if u care about u family and consider how they will feel if u kill u self ;and if u have faith and believe in god unlikely u will kill u self.