Complex sentence: They became engaged on the night of Kal's death in May 2015 and the following month, Leanne began enduring parental abuse from her stepson, Simon, as his behaviour spiralled out of control.
Split into simpler sentences: They became engaged on the night of Kal's death in 2015. From June 2015, Leanne endured parental abuse from her stepson, Simon, as his behaviour spiralled out of control.