Kate Garraway says she feels like she is on a "precipice" each time her husband Derek Draper temporarily regains consciousness.
The former political adviser, 53, remains in hospital after being admitted with coronavirus symptoms in March last year, before being placed in a coma.
TV presenter Garraway, also 53, appeared on BBC's The One Show to discuss an upcoming ITV documentary about their family's experience during his illness.
She said: "Derek is an extreme case. What he had is what is called a prolonged disorder of consciousness which means that there is some reaction.
"It is not like the coma we see in movies where people are lying in a vegetative state. He can open his eyes and before Christmas there was a lot of progress with words and communication and things.
"But what I feel like is that I am on a lifeboat somehow and he is coming up and down. Sorry, this seems very figurative but that is how it feels.
"You are on this precipice trying to hold on to him and there are moments when he bubbles up and you have some contact, predominantly at the moment on FaceTime because of the Covid restrictions.
"It feels like you are having to fill him with so much positivity because he is going to sink down. What you will see in the documentary is some of the better moments even though they are heartbreaking, I am afraid, where he comes up.
"Then you see what must be agony for him because he is somebody who, both in his time before I knew him when he was in politics and also since in all the work he has done in mental health, because that is his thing now, his brain has always been his best friend."
Garraway said her husband had "lived on his wit" but was now "fighting to get out".
She added that however hard her experience had been during his illness, his would have been more difficult.