Willie has done Elizabeth a huge favor. He has forced to think about what would be even worse than being exposed as a murderess. She has discovered the limit of what Jason can force her to accept, and now, even though she is still submitting to blackmail, she is stronger than she was.
I think that when Willie was looking at the portrait of Barnabas at the end of today's episode, it was the first time on the show that we heard a voiceover other than the opening "My name is Victoria Winters" ones. I imagine the writers regretting that Moltke's voiceovers will no longer be so special, but figuring it was a good way to help James Hall with his lines. My imaginings are probably completely imaginary, however: instead the writers may have been seeing it as paving the way for the heartbeat. First you hear what's going on inside Willie's brain, and then you hear what's going on inside the portrait's chest.
I love the heartbeat. It's used at other times later on in Dark Shadows, and doesn't particularly thrill me, but today I loved it. It's partly because I know what's coming and I know it's good, and partly because I can imagine not knowing what's coming. All I have to know is that there's an unknown force - a heartbeat in the heart of Collinwood. If it gets loud enough, it could shake the foundations of Collinwood, break the door of the locked basement room, and eject Paul Stoddard from his unknown grave. Has it been beating there in the foyer, unheard by anyone, ever since the portrait was painted?