You won't want to hear this, but I think you should step back. this person has been an online friend for 20 years, but it is only now, when you appear to be wanting to make a life for yourself, that he chooses to say that he "has feelings for you".
What kept him? Why has he not spoken before now?
It seems to me that this person is trying to control you.
If you let this happen you will never have the chance to form new friendships and make a life for yourself, as you feel you are now ready to do.
I think you should run a mile.