I have only just started to use this silicone rubber nipple, but it is already torn after a few use. Why is that so?

Silicone rubber can be slightly delicate, and sensitive to tearing. Also, since the rubber is thin at the tip of the nipple, it may tear as a result of physical force even if it has not been used so many times. The “Y Cross Cut Nipple” in particular tends to split easily, as it has notches in three directions as compared to nipples with round holes.

Please use a nipple cleansing brush when washing the nipple.

Push the tip of the nipple with your fingers so that the nipple brush does not break through the tip of the nipple when washing it.