I don´t know why as I became religious I feel like I will go to jahannam and Allah curse will be on me I have been very sad for days and I try my best to hold my tears
Sahih Muslim (2664): "A strong believer is better and is more lovable to Allah than a weak believer, and there is good in everyone, (but) cherish that which gives you benefit (in the Hereafter) and seek help from Allah and do not lose heart, and if anything (in the form of trouble) comes to you, don't say: "If I had not done that, it would not have happened so and so", but say: "Allah did that what He had ordained to do" (قَدَرُ اللَّهِ وَمَا شَاءَ فَعَلَ - Qadarul-lah wa ma sha'a fa'al) and your "if" opens the (gate) for the Satan."
Concerning your statement about how Allah thinks of a human being:
The Prophet (ﷺ) said: "Allah says: 'I am just as My slave thinks I am, (i.e. I am able to do for him what he thinks I can do for him) and I am with him if He remembers Me.“ in Sahih al-Bukhari (7405)
In another narration:
Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said: “Allah Almighty says: I am as My servants expects of Me. If he thinks good of Me, he will have it. If he thinks evil of Me, he will have it.” Sahih Ibn Hibban (639)
Shaytan often enough comes to the people, especially to those who have little or no knowledge, to deceive the hearts, to make sure that you feel miserable and alone. The Shaytan wants you to feel bad, weak, exhausted and that you might even get into the believe that Allah would hate you.
Allah says in Surah al-Baqarah [155-157]:
"And We will surely test you with something of fear and hunger and a loss of wealth and lives and fruits, but give good tidings to the patient,
Who, when disaster strikes them, say, "Indeed we belong to Allah, and indeed to Him we will return."
Those are the ones upon whom are blessings from their Lord and mercy. And it is those who are the [rightly] guided."
Sahih Muslim (918): "If any Muslim who suffers some calamity says, what Allah has commanded him, "We belong to Allah and to Him shall we return; O Allah, reward me for my affliction and give me something better than it in exchange for it," (Inna lillahi wa inna ilayhi raji'un - Allahum-majurni fi musibati wa achlif-li khayran minha) Allah will give him something better than it in exchange."
If you want to feel contentment in your life - Allah says:
“Those who believe (in the Oneness of Allah - Islamic Monotheism), and whose hearts find rest in the remembrance of Allah, Verily, in the remembrance of Allah do hearts find rest”
“Is he whose heart Allah has opened to Islam, so that he is in light from His Lord (as he who is non-Muslim)? So, woe to those whose hearts are hardened against remembrance of Allah! They are in plain error!”
“Therefore remember Me (by praying, glorifying, etc.). I will remember you”
“and remember Allah much, that you may be successful”
“and the men and the women who remember Allah much with their hearts and tongues Allah has prepared for them forgiveness and a great reward (i.e. Paradise)”
As you see by the verses of the Quran: Pray 5 times a day, and learn how to make the prayer properly (https://www.youtube.com/watch?v=T4auGhmeBlw), on how to recite the Quran properly, recite the Adhkar after every obligatory prayer and on the specific time in the morning as well as evening (Free PDF on the internet: "Hisnul Muslim" or "The Book of Rememberances" by An-Nawawi). Abstain from haram and make sure to educate yourself about Islam as much as you can per day to not fall for every trap or deception of Shaytan, and do not overexaggerate.
The Prophet (ﷺ) said: "There is (at times) some sort of shade upon my heart, and I seek forgiveness from Allah a hundred times a day." Sahih Muslim (2702a)
Ibn al-Jawzi said: "If you after a sin, feel darkness in your heart, then know that there is (also) light in your heart. Otherwise, you would not even notice the darkness."
Seek forgiveness from Allah as much as you can per day since it is narrated:
In Riyad as-Salihin (1873): "Ibn 'Abbas (May Allah be pleased with them) said: The Messenger of Allah (ﷺ) said: "If anyone constantly seeks pardon (from Allah), Allah will appoint for him a way out of every distress and a relief from every anxiety, and will provide sustenance for him from where he expects not."
Allah's Messenger (ﷺ) said, "Allah is more pleased with the repentance of His slave than anyone of you is pleased with finding his camel which he had lost in the desert. " Sahih al-Bukhari (6309)