再怎么见贱都比不上小三
[zài zĕn me jiàn jiàn dōu bĭ bù shàng xiăo sān]
Regardless how much someone tries hard to be humble, one can't match a 'third party,' a term commonly used for an intruding lover breaking up a married couple. It's often a bitter comment on personal relationship issues or competition with other people in relationships