I guess I should stop trying to "dissect" what's going on with H and just try to be happy since he hasn't left yet.

Amend that to "just try to be happy", period. Your happiness cannot be contingent on whether H is there or not. If it is and he stays, then you'll be "happy"... but if he leaves again, you'll again be devastated. You can't let this happen to yourself anymore. You must be happy from within yourself, and anything H does will not further impact on that. Once your happy comes from within, then if H leaves, you'll be disappointed and saddened, preferring to be with him, but not needing to be with him. That's quite different than how you are now, correct?

It's just been alot harder for me to understand why H has so much guilt... I get to thinking and this is when I start to hurt myself with all these thoughts - "why is H still feeling guilty?

Don't over analyze this. It's not doing any good, it's contributing negatively to your well being.

H (long pause): "What did you do last night?"
Me: "Nothing really." (Yes, I lied , but I REALLY didn't feel like getting the third degree. I'm sorry - I'm a bad girl .)
H (another long pause): "Nothing?...Who did you do nothing with?"
Me: "What do you mean?"
H: "You said nothing. Did you mean you stayed home? If you did then why didn't you just say that?"
Me: "I'm sorry I wasn't specific enough. How was your night?"

Excellent, don't you think? The pattern is always when you back off, pull away, remain vague, then H pursues. So, I'd say put a reign on your feelings and do not greet H with great enthusiasm when he gets back. I think you have this back and forth with him because when things look positive with him, you do seem to get somewhat enthusiastic and show it.

Look at this as if you're trying to get an alley cat to feed out of your hand. You can't make any overt moves, you can't say anything. You just have to have the food in your hand and the alley cat approaches cautiously and VERY SLOWLY. Even after the cat determines everything's safe and starts to nibble out of your hand, if you then try to coo and/or pet the cat gently, the cat backs off. So even at the point where the cat is comfortable enough to feed out of your hand, you still have to be cool.

The point where the cat wants to be with you and eventually then will follow you home is when you can move and speak softly.

I can't really explain why I feel like I'm "preparing".

Because you're dwelling on it and feelings follow thoughts. Change your thoughts and don't dwell on it, you need to detach further.