That’s a tough one. I am certainly not a theologian either but I will share our view on the subject.
God has a plan for all of us. None of us were put on this earth to just exist. Part of what we are to do on earth is “work out our salvation with fear and trembling”.
Frequently suicide is the work of Satan. Satan corrupts our thinking into believing that is the best way out of our troubles. Most of the time suicide is an extremely selfish act, indicating that it is not of God’s good pleasure.
The core of the question then is, “is suicide a sin” and the answer is yes it is IMO. It’s the same as asking is being gay a sin? Yes, it is.
HOWEVER we are all sinners. Galatians 2:19 comes to mind
19 “For through the law I died to the law so that I might live for God. 20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!”
So then the question is not did she go to hell because she committed suicide. The question is was she saved? Was she a believer?
There is a little ditty that goes
Here lays an atheist
All dressed up with no place to go
I’ll bet he wished that it was so…
So the technical answer is if she believed she probably went to heaven. And we mortals may never know that..we know not what she did on her death bed or in private before hand. These are the eternal varieties though, not everyone is going to Heaven. I am pretty sure my mother isn’t, and I know my grandfather didn’t but what I cant do is get bogged down with that and let it serve to minimize my service to God.
So, my advice is
A) Forgive yourself for doubts, guilt, shoulda woulda, coulda’s. That’s not productive and its not fair to yourself.
B) As Summertyme says, turn this pain over to God, pray to him and ask for it to be removed.
C) Never forget the concept of “there but for the grace of God go I”. (key word there is GRACE) I personally cannot tell you that I wouldn’t also have taken my own life if I was in your mothers state (God rest her soul) so it is most certainly not our place to sit in judgment of her.
D) Find something constructive to do with this experience. Life on earth frequently sucks..even for believers but we have a moral obligation to feel joy and appreciation and to walk that walk. Tests and challenges as well as favor and blessings are frequently generational in nature. What you do with said tests or blessings is completly optional. Here's hoping that you, all of us, can live, no matter what tests or blessings, in a way that "does not grieve the Holy Spirit"