Too Late to Apologize

Why would Betsy push her pregnant stepmother Shannon down the stairs? And why would her father Clifton barely care? After discovering his promise to his ex-wife Vienna to have no more children, and his willingness to sacrifice her over a business deal, Shannon demands a divorce. Yet Clifton suddenly fights to win her back, while Betsy goes from hurting Shannon to secretly protecting her. If jealousy wasn't the real reason behind the miscarriage, what was Betsy hiding?