Iam getting bad thoughts and insults about allah

Assalamualikum,
i am a 20 year old muslim boy. I am facing a problem from several days. I get bad thoughts and insults about allah and his prophet in my mind. I get very bad words about allah and i feel depressed after having such thoughts. These thoughts keep constantly coming to my mind whenever i pray salah ;and also in other times. Earlier these thoughts used to come only in salah but now they come all the time. I am also not sure whether i say these bad words in mind or did i utter it slowly because i have a habit of saying things to myself. I dont know how to deal with these thoughts. Will i be accountable for these thoughts (the thoughts are very bad sometimes i feel like i may lose eeman because of these thoughts). Thats why i am sending you this problem so i that i ca get help regarding this. Please provide me a detailed answer whether iamaccoountable for these thoughts or not and if iam accountable then how should i repent for it. I hope you will answer me soon because my anxiety is increasing day by day.