Thank you for improving my punctuation. Here are some more sentences I'm doubtful about.In particular, I find it difficult to express numbers 7 and 9.
1) However, while looking at the picture, a cry of pain and indignation comes from him.
2) He can see no change in it, except that in the eyes there is a look of falsity and on the mouth a smile of hypocrisy.
3) He realizes that it was only out of vanity and hypocrisy that he (had) spared the young girl.
4)He considers his portrait loathsome and he feels sorry and guilty towards (of) his way of behaving.
5) The portrait has recorded all the negative actions and murders he (has) committed in the past.
6) It has become the mirror of his corrupted soul, of his double personality .
7) Since the mirror is the only evidence against him, he decides to destroy the picture, thus getting rid of his own conscience.
8) He looks around and sees the knife that he used to stab Basil. He seizes it and stabs the picture with it.
9) As his conscience is an intrinsic part of himself, he kills himself by stabbing the picture, which becomes beautiful again. Dorian, instead, becomes repellent, old and his face shows the signs of his sins.
1 and 2 are fine.
Keep "had" in #3.
4 - comma after "loathsome" - delete "towards" and "of" and insert "about"
5 - delete "has"
6 and 8 are fine.
7 - change "mirror" to "picture" and change "picture" to "it"
9 - "... becomes repellent and old, and his ..."