why don't you just give it a go. He will be there if you fall over but maybe he thinks you are ready for this, you just don't yet realise it. New things are always scary but if we all avoided trying these scary things we would never get anywhere. I prefer to try something, give it a go - people can do amazing things when they have to and I find there is no better motivation than someone pushing me. You are already amazing by getting this far.
Look at it this way, what is the worst that could happen? you obviously already feel pretty crappy at the moment, and if it doesn't work out, you have just wasted one or two sessions which isn't much really.