Help settle a debate with my husband!

Here's the situation -

I work for government and return to my job soon after a year on maternity leave. I've stayed in contact with lots of colleagues/friends during that time. A recent change to the department I'm in means my job is a bit up in the air, and last time I spoke with some of my colleagues I asked them to keep me up to date with whatever they hear about what is happening etc that might impact my job.

At about 6 or 7pm last night one of my colleagues (who happens to be male) sent me a facebook message letting me know that there's a big meeting next week for all staff, where they will likely discuss the recent changes/implications at work. At the time I was watching a show with hubby that we watch together every week, so I ignored the message on my phone (along with a couple of other messages from my best grlfriends). At maybe 8pm after the show, I responded to messages from 4 people including the colleague, and I went to bed soon after.

I woke up at midnight to breastfeed bub and sat on my phone afterwards as I do every night (not great for sleep, I know). Since I'd gone to bed the colleague had replied again, still about the changes at work, and I replied to that message. Hubby came to bed soon after and heard a notification on my phone - the colleague replying again, still about the work stuff. He asked who it was and I said it's a colleague letting me know about changes at work. He asked again who, and I again said a colleague (didnt give a name as he doesnt know him so I guess I figured it was meaningless). He asked again and i said it was a guy from work and gave his name. Hubby was anxious about it so I handed my phone over for him to see all the messages.

Hubby was then furious, essentially because i have messaged a male during the night. Cue raised voices, him calling me a liar and saying I hid it from him, and him sleeping in the other room. We argued about it today and we are still barely talking.

(If you've made it this far, thanks for reading! I didnt want to leave out any detail)

My question is, have I done anything wrong???

Have I been disrespectful?

There is ABSOLUTELY NOTHING between me and the colleague. It wouldnt matter if he was male or female, I have never thought of him that way. I remember that he is a night owl as I remember he used to talk to everyone at work about how late he stayed up and he wouldnt talk to anyone at work in the morning as he wasnt a morning person - so I dont think it's weird that he messaged in the evening. He's also married with kids, and talked so highly of them all. I'm totally confident he wouldnt think of me as anything other than a colleague too.

I told hubby i often reply to emails and messages at night as it's when I catch up on things when my daughter is asleep and when I cant sleep. This is anything from emails from the real estate agent to gumtree ads to messaging my best girlfriends. Hubby has asked me to send any message to any male at night. What do you think?

Thanks for reading this mammoth post!! Let me know what you think, I'm going crazy.