Alicia Watson constantly texted her former partner complaining about being unable to party with her friends due to being a mother, the trial was told.
Watson, 23, and her boyfriend Nathaniel Pope, 31, are both accused of murder and child abuse.
Mobile phone messages read out to Birmingham Crown Court revealed that despite living with Pope she would besiege her ex-partner for drugs and have sex with him.
Darren Darby, the father of three-year-old Kemarni, took to the stand for the third time and was cross examined by defence lawyers.
He was asked if he sold drugs to his ex-girlfriend, and messages of a sexual nature between the two were read out in court.
Mr Darby repeatedly denied being a drug dealer.
The court also heard Watson used to complain about not being able to go out and party because she had to look after her children. Watson would also send Mr Darby voice notes of Kemarni pleading to see him.
Previously in the trial the court heard Kemarni had often tried to escape in the weeks leading to his death. The toddler sustained massive injuries and internal bleeding with his rib cage being fractured 19 times in one violent encounter.
He also complained his "belly was falling down" hours before he died of massive internal bleeding on June 5, 2018. Darby had previously testified he had been concerned how strict Alicia was with their child and noticed marks and bruises on his face and body.
The jury have been told proceedings will now run into February.
Watson, 23, of Raglan Road, Handsworth, Birmingham, and Pope, 31, of Evans Street, Wolverhampton, both deny murder and charges of child cruelty.
Watson’s defence team claim she was a loving mother who made the tragic mistake of leaving her son with Pope.
The trial continues.