Jessica Simpson is slowly coming to terms with the breakdown of her parents' marriage.Joe and Tina Simpson - who are also parents to singer Ashlee Simpson - have ''amicably split'' after 35 years together and although Jessica is saddened, she is trying to get on with her life. A source told People magazine: ''She's going on with everything. She's sad but she's fine.'' Tina filed for divorce papers in Texas on September 24, stating: ''The marriage has become insupportable because of discord or conflict of personalities.'' The couple put their $4.4 million mansion on the market earlier this month amid speculation they were living apart. Jessica is being kept busy looking after her five-month-old daughter Maxwell and planning her wedding to fiance Eric Johnson. She recently said: ''Motherhood is a dream. It really is absolutely amazing. [Maxwell] had her first flight recently. Did not sleep! She didn't cry. She just wanted to babble. ''People call Eric the best dad in the world. Even my dad calls him that! He can do everything. He can change every diaper . . . he's just a very peaceful person.''