If you wish to accomplish a fade, rather than it coming to any kind of confrontation resulting in a DA or DF then you must be prepared to be "economical with the truth" as our British politicians call it.
Reply that you are feeling unwell just now, but that you hope to go in the service with him, but you may not attend a meeting before then, you will text him to make arrangements, thank him for caring, say "you are a real friend".
At the weekend fob him off some more. Now, will you attend the Meetings again ? just for "appearances" ? you don't say.
if you are, then seek him out and tell him you have a form of depression which you are working on, you will keep in touch with him, and as soon as you feel well enough you will be out with him and back to all the meetings.
If you don't plan to go to Meetings, then adapt that message.
Fading is not easy, but remember, time is on your side, they cannot rush or force you, play the depressed card, even claim to be suicidal if you like, they will back off for a good while, then just tell them that you will contact them when you feel well enough.
Most Elders and MS have limited stamina, fob 'em off long enough and they lose interest, the longer they leave you the more difficult it gets for them, not you.
Good Luck !
p.s this is complicated if you live in a household of JW's who know you are far from ill or depressed. If that is the case you may need to consult a doctor and fake it a bit.