You're a seasoned commuter Mag - you know how it works. Don't beat yourself up! The thing IMHO is to be flexible in your approach to cycle commuting. For years I used to commute in every weather and right round the year. Nowadays, I give myself the opt-out...
if the weather is pants and I don't feel like a soaking / risking icy roads
if I feel under the weather myself in any way
if the legs have had enough of the hills for a few days
if Mrs Beanz has kindly offered me a lift home at the end of the day (rare, but it happens!)
if I can't face sorting the bike out in the dark when I get home
Surprisingly, this isn't really that many days a year (and nearly all of them are in Winter). I'd rather not risk damaging the bike / damaging me / having a miserable commute. The days that it does affect, I take public transport without feeling any remorse about not being on the bike.