This translation will stay on the blog for two weeks, so do download it if you need it . If you just chanced on the blog, the original passage translated can be found here .
Suggested translation Mauriac
After the children had left, Xavier Frontenac watched his sister-in-law once more : she still looked hostile. How might he have offended her ? He had spoken of dutiful women, of which she was the perfect embodiment. He did not understand how such praise could exasperate a widow such as she. The poor man had gravely praised the nobility of sacrifice, and had declared that nothing in the world was as beautiful as a woman faithful to her deceased husband and devoted heart and soul to her children. In his eyes she only existed for the Fontenac offspring. He never thought of his sister-in-law as a solitary young woman who could feel sadness or despair. Her fate was a matter of complete indifference to him. Provided that she did not re-marry and she brought up Michel’s children, he reflected no further on her case. This was what Blanche could not forgive him for. It was not that she felt any regret : on her husband’s decease she had weighed up the sacrifice she was called upon to make and had accepted it ; nothing would have made her go back on her decision. However, since she was most pious, in a somewhat arid and pernickety way, she had never believed herself able, but for God’s help, to find the strength to live in this way ; for she was a passionate young woman with a fiery heart. That evening, if Xavier had had eyes to see, he would have felt pity for her, left amidst the books scattered on the carpet and the untidiness of the forsaken nest, a tragic mother, with eyes of jade, and a bilious, furrowed face, where some remnants of beauty still resisted the wrinkles and the weight loss. Her hair, already grey and a little untidy, made her an unkempt appearance as of a woman who no longer hopes for more. Her black blouse, buttoned up in front , emphasized her thin shoulders and small bust. Her whole being betrayed the tiredness, the exhaustion of the mother devoured alive by her offspring. She asked not to be admired or pitied, but to be understood. The blind lack of concern of her brother-in-law caused her to be beside herself with rage, and she became brutal and unfair. She regretted it and beat her breast in penance as soon as he had left, but all her good resolutions came to nothing when she saw once more the expressionless face of that small man who could not see and before whom she felt non-existent, that man who had her marked down for oblivion.
François Mauriac Le Mystère Frontenac
 The style is definitely literary, and there are many places where we must avoid the everyday word and use the more literary or formal one – « Provided that » rather than « as long as », for example.
 Remember the preference of English for verbal constructions.
 “Once more » or « once again” are better here than just « again » becaus ethey make for a more literary tone.
 Or « she had not been mollified ». Or « her anger had not lessened ».
 If you were tempted by « would » re-read the whole section on modals in your grammar book.
 Note that « talked about » is not as good, since it is less formal.
 Or « of which she was the epitome » .
 Here, « praise » is an uncountable noun. It can occasionally be countable, as in, « they were singing your praises », but in general it is uncountable.
 Notice that « insisting heavily » is French, really.
 « Could » is better than « might » here, since we are in radical modality : it is her capacity to feel, not the probability that she might feel, which is in question.
 Although this list has only two items, the items cannot be joined, as they can in French, only by a comma.
 Or « What became of her ».
 « Re-marry » is more formal than « marry again » or « get married again ».
 Be careful: the meaning of the French is that she felt zero regret, but the literary style led some students astray.
 Not « measured ».
 « But » is not formal enough.
 Somebody tried « intense », but this is not correct. If we say someone is « intense » it is a rather pejorative comment, meaning that they invest a lot of emotion in matters which should not involve so much feeling.
 Not « the rug ». A rug is small enough to carry under one arm.
 One cannot say here « a neglected woman « , since that would not refer to her appearance.
 These imperfect tenses in French are just background description, and so are translated by the preterite. Certainly, you must not use « would », which is for habitual action.
 « Eaten alive » is good. Someone trued « eaten up alive » but « up » generally implies « completely », and here the process is not finished.
 This structure is more literary than « she did not ask… »
 I am realizing that « violent » in English involves physically hitting someone, whereas « violent » in French does not.
 The sense is figurative, and this is a fixed expression.
 Someone tried « eyeless ». This is an extremely rare literary word which means literally without eyes. The only place I have ever seen it is in Milton’s impressive poem, Samson Agonistes https://www.bartleby.com/4/602.html
 Or « who consigned her ».
 «Who doomed her to nothingness » is good.