Hi, I've had my Jade plant for many years and I think its starting to die and I dont know what to do with it. Can anyone help?

Assuming you have watered regulary its likely suffering from root rot. I would recomend removing it from the pot to inspect the roots If they are rotten cut them off and then plant it in new dry cactus soil. Don't water for a while but mist it heavily every day. Hope this helps.