When my son became ill with depression and social anxiety he stopped attending school. I began making excuses for his absences - to both the school and his friends. After this happened repeatedly, and for prolonged periods, I found that I was unable to continue lying about the true nature of what was going on. I told the school and told the parents of his friends exactly what was happening. Their response was the opposite of what I expected. The school jumped in to offer support and approached his absences with empathy and concern and his friends and their parents were very supportive in any way they could be. The same bridge had to be crossed when I chose to openly disclose the domestic violence that I was experiencing and I again found supportive reactions - far removed from what I had imagined.
My advice would be to be truthful about what is happening, however you will need your husband's consent to do this as it is ultimately his personal problem. I think both you and your husband would be very suprised with the support that your friends will give you. If your husband is not keen or amenable to this you might just like to advise your friends that he is "not well" rather than have to create untruths. Mental illness, particularly depression, are commonly accepted by most people these days. You may even find that they have their own stories and experiences to share with you.
As a worthwhile exercise it may be useful to ask yourself (and/or your husband if appropriate) exactly what it is that prevents you from telling them the truth. Fear of judgement and all the perceived consequences of disclosure are worth exploring - do you fear rejection from your friends? etc, etc. Ask yourself this question .... if a friend told you that her husband was suffering with depression and that they were unable to attend an event, how would you reply or what would you say? Then ask why you think they would answer or respond differently.
Mental illness is part of life. It is a bold but essential step to disclose this to people so that awareness is increased and the stigma surrounding it is decreased. Disclosure of his mental illness will allow people to fully understand what is going on in your life and take away the need for you to hide his/your experience. It also opens the door to allow others to share similar experiences and ultimately aids you as a carer because you will feel supported and not as isolated. In many ways it also aids recovery for the individual that is suffering because it reduces the stigma and increases their support network as well.
Remember that you have full control over exactly how much information you want to share at all times. Just last week I was purchasing a pair of runners for my son without him and by using the innersole of another runner. The girl serving me asked what sort of sports he was into and I replied "None". She asked what physical activity he was engaged in e.g walking, hiking, etc. She was merely trying to find the best fit for purpose runner. I responded by saying that he did not engage in any activity because he suffers with depression. She immediately replied by telling me that she also had suffered with a terrible depression herself for several years and then went on talk sympathetically about it and how her parents tried everything, etc. Rewind 4 years ago I wouldn't have dared mention this to anyone.
I hope this helps answer your question.
Take care
Janna ❤️