Like Johnny Boy Soprano, her awful treatments of Tony played a major part in shaping his self-image and his views on people. Not only that she's a bitter narcissist and a bubble of cynism and nihilism who only derives pleasure from making the lives of the people around her a miserable hell. She's a manipulative bastard who was able to plant ideas into people's head like urging Junior to place a hit on her son and telling Artie that Tony is the one responsible for the destruction of his restaurant (in which Artie responded by pulling his sniper rifle at a confused Tony), putting his life on the line twice and when Tony confronted her, she starts grinning which understandably infuriates Tony. This incident obviously affected Tony as he asks Dr. Melfi: "What kind of person can I be, where his own mother wants him dead?" And since then he wasn't able to fully move on from her affect on him, dooming in the process into accepting nihilism and becoming a worse version of her. She also mentally abused Tony's son AJ by feeding him her nihilistic outlooks on life, in which the latter took it as an advice and starts displaying signs of apathy and disregard for human life. Her words are arguably the main cause for AJ's mental decline, depression and his suicide attempt in Season 6. He even quoted her "Life is a big nothing" line during his therapy session with both of his parents.
Now when it comes to the Heinous standard, she managed to orchestrate two attempted murders on Tony, indirectly cause AJ's suicide attempt and be the catalyst for Tony's actions throughout the show with way lesser resources than most characters in the show (being simply a mother and a housewife). Not to mention her personal villainy with Tony which like mentioned led him to a dark path where he descended into complete degeneracy and cruelty at the end of the show.
Her preventions however is that she did genuinely enjoy spending time with AJ and she seemed happy when he came and visit her. Also, she spared Christopher's life when Junior suggested killing him because she appreciated him helping her with the shores in her house.
What do you think guys?