What did you say? That matters. If it was like he has the smallest dick I've ever seen or I always fake it with you etc then he may never forgive you.

If you genuinely want to improve then do so. The first step is talking openly about it. Tell him you want to be better and ask what he would like you to do. Take baby steps and work your way to being just as involved. As others have pointed out men are told all the time that they are not good enough in bed, but lots of women in their early sexual experiences are super passive and just expect the guy to do all the work