Courtney B. Mathews v. Tennessee

Does a criminal defense attorney becoming a witness against their own client due to that attorney’s intentional and deliberate waiver of attorney client privilege, both pretrial and post trial, due to a personal ethical burden that causes them to act against their own client’s interests in favor of their client's co­ defendant's interests, create such divergent interests between said attorney and their client, as to rise to the level of an actual conflict of interest as defined in Cuyler v. Sullivan, 446 U.S. 335, (1980)?

If the answer to this question is yes would multiple trial errors attributable to the documented deficiencies of Counsel, during the actual trial itself, be properly reviewed under the presumed prejudice standard of Cuyler or more appropriately reviewed for cumulative prejudice from distinct errors under the Due Process Clause as applied in Chambers v. Mississippi, 410 U.S. 284, 294 (1973)?