All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Dear brother, your problem is that you have ignored this disease till it captured your mind and causes you all the problems you mentioned in your question. If you had used the remedy prescribed by the Prophet you would not suffer the current situation. Know that Allah has sent a cure for every disease. The remedy for your illness lies in the saying of the Prophet : “The devil would come to one of you and whisper to him: “Who created such and such?”, “Who created such and such?”, until he whispers to him: “Who created your Lord?” If things reach this level, he should seek refuge in Allah from the devil, and stop asking [thinking about] such questions.” [Al-Bukhari and Muslim]
If one lets oneself go to such thoughts and pays attention to them, then they will grow and increase and go beyond limits. After that, the doors of doubts and of such questions will open, which are difficult to close; and other doors will be opened and this continues. Whoever takes such doubts seriously will become confused and doubtful in all his knowledge; yet, after sometime, he will blame his mind and senses and will become as the one whose situation is mentioned in this verse (which means): {And [even] if We opened to them a gate from the heaven and they continued therein to ascend. They would say, “Our eyes have only been dazzled. Rather, we are a people affected by magic.” And We have placed within the heaven great stars and have beautified it for the observers.} [Quran 15: 14-16]
The useful solution for such problems consists in the three following matters:
1) Seeking Allah's refuge from the whispers of the devil.
2) Resisting such whispers and repeating the words of faith to disparage them.
3) Neglecting them and becoming busy in useful matters till they vanish without having any effect.
All the above solutions are for the whispers of the devil while they are still in their primary stage, but if they become strong and take root in one's heart, they are no longer considered only whispers since they now form doubts and lead to lack of trust in the Sharee'ah. The solution of this stage of doubts is to find a way to get rid of them and to take serious steps for their removal.
Consulting knowledgeable Muslim scholars to know the clear proofs and evidences that remove the doubts and satisfy one. Allah stated many proofs in His Book.
Allah Says (what means):
• {O People, if you should be in doubt about the Resurrection, then [consider that] indeed, We created you from dust, then from a sperm-drop, then from a clinging clot, and then from a lump of flesh, formed and unformed - that We may show you.} [Quran 22: 5]
• {And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a surah the like thereof and call upon your witnesses other than Allah, if you should be truthful.} [Quran 2: 23]
• {So if you are in doubt, [O Muhammad], about that which We have revealed to you, then ask those who have been reading the Scripture before you. The truth has certainly come to you from your Lord, so never be among the doubters.} [Quran 10: 94].
Dear questioner, what we mentioned above is the cure mentioned in the Book of Allah and the Sunnah of His Prophet .
To think that finishing your life will bring relief is wrong; rather, this will only lead you to a greater unhappiness by the torment of Allah. It is confirmed in an authentic Hadeeth that whoever kills himself using any means will be punished by the same means in Hellfire.
Know that regardless of how serious the problems are, killing oneself results in the loss of this worldly life as well as that of the Hereafter.
For more benefit on whispers about Allah, Kufr and creed, please refer to Fataawa 396772, 389311, and 18353.
Allah knows best.