Breaking down your opening post, OP:
I've been ill with Covid for weeks and haven't been able to get out of the house. Struggling with energy and needing to sleep a lot.
That's very hard for you but it will also have an effect on your wife.
Honestly, I was feeling overwhelmed with work and just life before I got physically ill and haven't been much fun to be around.
Did you do anything to address this prior to catching Covid? Being ill with Covid has exacerbated what seems to have been an already difficult time for your wife.
Lots of things are getting to me, but I keep being told by my wife it's just because I don't feel well. Things around the house that need fixing and keeping on top of, apparently I'm just moaning
Be honest, are you just moaning? What do you expect your wife to do and/or say about things around the house that need fixing or keeping on top of? Do you want her to do them?
Neighbours constantly disturbing me all day long is just me whinging.
Again, what do you want or expect your wife to do about this? Maybe she is just fed up with you constantly going on about it.
I'm dull and unpleasant and just have a problem with everything.
Are you and do you? It sounds as if you were struggling before Covid and are getting worse, what have you done to address this, what are you going to do to address this?
I'm being dramatic to say I feel hopeless and like I have nothing to look forward to. I just shouldn't say it. It's abusive of me to say I see no way out, because I only want her to agree with me and she doesn't, and doesn't want to hear it.
Again, what are you going to do about the way you feel? Your wife cannot fix you. It must be very upsetting and disheartening for her to hear that you have nothing to look forward to, can you not see how saying that would make her think you don't value her or your future with her?
My wife hasn't spoken to me since she said these things and has gone out. I didn't think I could feel worse but I don't know what to do.
You do sound unrelentingly negative and that is very draining on a spouse. You need to become proactive in managing your mental health, to start with contact your GP and explain how you are feeling and that you felt like this prior to catching Covid. You wife cannot cure you or fix you, only you can do that.