Gusts are wind bursts of up to 20 seconds, they may be short lived but you should take these into account, so you should use the gust speed, not the steady wind speed. If you are on short final close to your crosswind limit and a gust comes that's higher than your control surfaces can compensate for it doesn't matter how good a pilot you are, the airplane is going to go sideways and there's nothing you can do to prevent it. A brief burst may not sound like a lot but it only takes 2-3 seconds to blow you off the runway.
As painful as it may be you have to take the gust values and your own personal capabilities as a pilot into account. That doesn't necessarily mean that having gusts over the limit is an automatic no-go, there are mitigating factors to consider, especially if it's very close to the limit. Shelter helps, the airfield I fly from has some woods which shelter the landing end of one of the runways, which is the one that's most frequently in use. These woods moderate the wind and gusts from the west, which is prevailing, so I often can fly in higher winds.
The OP is probably well aware of this, but a well rounded answer needs to mention wind direction and calculating the crosswind component. Wind direction is also a consideration, the calculation is V x Sine degrees of crosswind. 30 degrees is 50%, 45 degrees is 70% and 60 degrees is %85. This is hard to calculate in the air, it's easier to say that 45 degrees is 75% and 60 degrees is 100%, and gives a bit of 'fudge factor' for safety. So, if you have a 45 degree crosswind at 20kt gusts you are within limits.