The Catholic teaching is that perfect contrition is the best, but imperfect contrition is sufficient for a valid confession. I think some people refer to imperfect contrition, so say sorrow is not needed, or that contrition does not require an emotion, rather a firm will.
Baltimore Catechism No 3.
Q. 753. What is contrition, or sorrow for sin?
A. Contrition, or sorrow for sin, is a hatred of sin and a true grief of the soul for having offended God, with a firm purpose of sinning no more.
Q. 765. What is perfect contrition?
A. Perfect contrition is that which fills us with sorrow and hatred for sin, because it offends God, who is infinitely good in Himself and worthy of all love.
Q. 767. What is imperfect contrition?
A. Imperfect contrition is that by which we hate what offends God because by it we lose heaven and deserve hell; or because sin is so hateful in itself.
audiosancto.org/inc/BC3/bc3-18.html