I need to split some text but means a single and is an indicator for a literal character. I have started with the following code but it is fooled by

string message = @"1#2\#3#3#still 3#4\# still 4";
var v = Regex.Split(message, @"(?<!\)#")
        .ToArray();

I would like the message to come out as
1
2
3#still 3
4# still 4

but cannot figure out how to ignore the instances so mine comes out as

1
2#3
3#still 3
4# still 4