Complex sentence: Tamsin is also pregnant, as a result of a drunken one night stand with a lad from university, and she and Virginia decide to raise the child together-until Tamsin realises that Virginia is still obsessed with Megan.
Split into simpler sentences: Tamsin is also pregnant, as the result of a one night stand with a guy from university. She and Virginia decide to raise the child together until Tamsin realises that Virginia is still obsessed with Megan.