I have a habit of taking a very long time to reply to emails and messages. Since some of these are from friends with whom this is my main form of contact (i.e. unless it is organised via messages and/or emails, I will never see or speak to these people), it's important to me that I keep these channels of contact open.
After a while, I will realise that it's taken me too long to reply, and I should put it right, but I then find myself having to explain why I took so long to reply. Since the reasons for my terrible response times are usually a bit stupid, difficult to relate, and could potentially offend people (e.g. "I got super obsessed with a writing project for a couple of months, and I kept not getting around to it"), I usually end up delaying the reply even further until I've "thought of a good way to explain".
Since I never (or very rarely) do think of a good way to explain, the delay just increases, until it seems to me that no explanation of how long I took to respond can possibly be adequate and that I have probably already offended - and almost certainly been disrespectful to - the original message sender.
What can I do at this point to reopen communication, and reassure them that I didn't mean them any disrespect?
To clarify, I'm talking about communication with friends, here. Usually these are friends that I'm not close enough with to see very regularly, but close enough with that I want to keep in contact and occasionally spend time with them.