The short answer: there are several methods for coping

The Basic Technique (“BT”) calls for masturbating your G-spot.  Sometimes, stimulating the G-spot can lead to pleasure that is too intense, overwhelmingly intense.  The intensity can lead to stopping masturbating.

Encountering intensity that overwhelms you is natural, and normal.  The good news: there are several methods for reducing the intensity to a level which is enjoyable again.

If you encounter overwhelming intensity, there are several things to try.  First, try easing up on the pressure you are applying to your G-spot.  A lighter touch may be all that is needed.

Second, as orgasms was over you, intensity tends to grow over time.  So, you may need to adjust, using a lighter and lighter touch as you go along.

Third, try stimulating another erogenous zone instead of your G-spot.  Once you begin having orgasms, brushing or pulling on your pubic hair may provide enough stimulation.  If that leads to too much intensity, try touching and rubbing only your nipples.

A combination of both brushing or pulling on your pubic hair and stimulating your nipples is also worth trying.

Fourth, try taking a couple of deep breaths.  Breathing deeply tends to reduce the intensity.

Experimenting in this way will typically enable you to find a way of coping with, and managing, the intensity.

Enjoy the journey!