Mrs. Kavinsky is not described within the books.
She and Peter have a good relationship, most likely because Peter is her first son. She also describes him as being "completely different from his father", especially because Peter is very loyal to the people he loves, unlike his father.
Owen is Mrs. Kavinsky's youngest son.
According to Peter, Mrs. Kavinsky doesn't dislike Lara Jean but rather is afraid that she will hurt Peter again after the events of To All the Boys I've Loved Before and P.S. I Still Love You. She also believes that Peter is too loyal to Lara Jean, fearing that he will make the same mistake as she did and settle for someone at a young age.