Netty, I think fear comes with age (I have no idea how old you are, but you are a returning rider, so you are older than you were). We are much more aware of the stupid things we did as teenagers, it is normal to be fearful and want to self preserve.
However you want to ride for a reason, and it is different from riding a bike where you are in complete control, the bike cannot think or react itself. That's the beauty of riding a horse that we can in some way master them.
My advise would be to figure out what your goals are and focus on them.
You can do it. There are 23,000 members on this board and we all do it, and it's not because we are any better human beings than you!