Complex sentence: Ted reminds Marshall of the first time that they met in college, before Marshall had met Lily, and that he is someone outside of his relationship with Lily and encourages him not to let his break-up ruin his life.
Split into simpler sentences: Ted reminds Marshall of the first time that they met in college, before Marshall had met Lily. Ted tells Marshall that he is someone outside of his relationship with Lily and encourages him not to let his break-up with Lily ruin his life.