The 98 Degrees singer - who has a seven-month-old son Camden with his second wife Vanessa Minnillo - hasn't talked to the 'Fashion Star' mentor in six years and never reminisces about their old reality TV show 'Newlyweds', which documented three years of their married life before they split in 2005.
The 39-year-old star told Andy Cohen on 'Watch What Happens Live' on Tuesday (07.05.13): ''Wow. Is this the part where I can plead the Fifth? It's been years (since I've talked to Jessica). Years. Honestly, probably six years. It was like another lifetime ago.
''I have not (watched 'Newlyweds'). As you can imagine, that's not popular viewing in my house. We don't sit around as a family and watch the old DVDs.''
Nick also poked fun at Jessica's father Joe Simpson, whose divorce was recently finalised from her mother Tina amid rumours he is gay.
Asked what is the best thing about no longer being related to Joe, Nick's brother Drew Lachey quipped, ''everything'', before he eventually replied: ''What is the best thing about not having Joe Simpson as a father-in-law ... I don't have to play grab a** under the table on Easter Sunday.''
Jessica, 32, is set to give birth to her second child with her fiance Eric Johnson this summer.
The fashion designer's daughter Maxwell celebrated her first birthday on May 1 and Jessica confirmed a few months ago that she is expecting a baby boy next.