Of course you feel bad. By staying at work you can convince yourself it's not really happening. I've done exactly the same. Two suggestions: decide on a period you're going to stay off and stick to it - get the GP to sign you off for(say) a fortnight, then use the time to really chill out and try to gather your strength up. OR, have the conversation where you negotiate with your colleagues to do most of what you have to and (for example) work an hour less each day/come in later in the morning/miss meetings/don't do overtime - whatever could be agreed. It could be helpful to talk all this through with the GP, who might have an idea about what's realistic and what's not. The worst of all worlds would be to make this period of un-wellness longer than it needs to be. Take advice, then have the conversation with the folk at work. I'm sure it'll come over as you wanting to make the best of a bad situation and not taking advantage of their goodwill. After all, if it is was one of your colleagues in this position, wouldn't you want to help?

Thank you, that's really good advice. I need to stop pushing myself too much as it only makes me get these bad relapses that take ages to get over. I do need to rest a correct amount of time and stop fooling myself that I'm fine, as I keep telling everyone that asks me. Thank you