I identify with so much of what you're saying in this and the other thread.
It's been over two years since my boyfriend disclosed to me, and since I learned about his acting out and lies over the course of our relationship.
I think I spent the first 20 months of that time scared out of my mind. Every time he took a deep breath before he spoke, I went into panic mode-- Oh my god, there's something else.
And I said the same stuff I hear you saying to him-- "Just don't lie to me anymore. I can handle anything you have to say to me as long as you say it NOW, don't make me find out again, don't make me feel betrayed and untrustworthy again."
I had to say that TWICE in the first year.
But when he's feeling low I realise that when I've talked about my needs sometimes he doesn't hear "I need you not to lie to me" He hears "You are an untrustworthy, lying piece of cr*p and you'd better change your ways entirely (or something equally vague) or I will leave you, attack you, etc etc ....."
This is just my opinion, but to answer your original question, I think that support becomes enabling when you stop communicating your needs, or sticking to your boundaries, because of what he may hear.
He needs to know what is going on with you. He needs to recognize that there is always a gap between what a speaker means and what a listener hears, and not make you responsible for the things that you're not saying.
My boyfriend needed to know that I wasn't calling him a lying anything-- I was telling him that I was insecure--and I'm sure he felt some guilt/shame/etc. about that-- but not telling him at all just makes us both victims.
There is a difference between fault and responsibility. At my boyfriend's job, if a delivery doesn't come in on time-- that's not his fault-- however, it's his responsibility to deal with the consequences-- is he just going to sit back and tell his boss, Oh, well, the delivery didn't come so I couldn't do anything-- or is he going to make some phone calls, try to find what he needs somewhere else, talk to customers about the problem?
Our relationship was very messed up for a while. It didn't have to be his fault, or mine-- but now we were the ones who needed to fix it-- and honestly I wouldn't have stuck around with someone who couldn't be responsible for doing his share of the repairs. I don't think that makes me less compassionate.