] I do not think she has anything against Louisa nor mind that Captain Wentworth might marry her, I believe that it is all to reassure herself that she was right in separating Anne and the Captain because if he can be charmed by Louisa he is even more unworthy of Anne.

Yes. She feels justified in her separation of Anne and Wentworth, if his judgment is so lacking that he could settle for someone like Louisa after having known Anne. Louisa is a nice and amiable girl, but even Anne thinks herself superior to her, and that "she would not have given up her own more elegant and cultivated mind for all their enjoyments." (ch 5)