Here is something from my notes..
Agrippina's power gradually weakened as Nero came to take charge of the government. One of the first signs that Agrippina was losing her firm control over Nero was his love affair with a former Greek slave Acte. Agrippina feared the influence Acte had on Nero and she became extremely jealous, she was consumed with rage. She tried to mask her feelings but all too obviously Agrippina [changed] from excessive severity to extravagant complaisance (Tacitus). This did not fool Nero and his friends warned him to beware of her tricks. Agrippina, fearing her own demise, threatened Nero by claiming that Brittanicus was the true heir to the throne. This very much alarmed Nero and cause him to arrange the death of Brittanicus.
Burrus and Seneca, reneging on their earlier understanding with Agrippina because they probably resented a woman having so much power, advised Nero that Agrippina was trying to take all the power for herself. They feared she was going to turn Rome into a petticoat government. (Scullard). Nero took their advice and his mixed feeling towards his mother changed for the worse. He ordered her residence to be moved to a separate mansion outside the palace and her portrait was removed from the coins. Nero finally realised that the woman was too formidable to be allowed to live, no matter how far from the palace, he resolved to having her murdered. she would be too formidable wherever she might dwell. (Tacitus). He had her set forth in the bay of Naples in a boat design to sink, but she swam ashore. Eventually she was put to death at her country house. Agrippina thus was killed by her own son. She had made him emperor by following an unswerving manipulating and murderous path, but her continuing interference became too much for Nero.