Yes, I am afraid of posting or sharing gambling related topics in my personal facebook it's because my partner don't like gambling also his relatives while in my side they don't bother about it since we really gamble.
What if she caught you gambling online and you accidentally shared any gambling related post? Why not tell her that you are engaged with gambling? I don't think there's a problem with that thing, just tell her that you are not that severe addicted gambler. Before I was so scared to share about gambling but a little by little I realize that I shouldn't share any of them either. 
I haven't experienced the life of a married person.