Good question, but unfortunately I think only your max hp increases. That said, the new max hp is there, so go ahead and heal the number of new hp you got.

Apa getting tired of these thugs swing again at the thug attacking her after deflecting his wimpy attempts

Attack: 16 Damage: 6

On a hit and the thug is still alive

She will cast divine smite 6 

(Okay, Sirrus is now at 10 HP. I just let it do what it wanted to, and that's what it did.)

The dice rolls hasn't appeared on dnd beyond for some reason, Antlan

Let's try again

Longsword: Attack: 12 Damage: 11

if hits disadvantage on next attack

Divine Smite: 13

Your divine slash cleaves through his chest, leaving a massive scar that glows with brilliance. Despite being a drunk, he mumbles something, although clearly missing a few words. "You've... stronger. Yes?" He is bloodied, and odds are one more hit should take him down. The thug(1) who was on the ground stands up, taking the dodge action. 

It is now Sirrus's turn.

Sorry, I'm slightly detached right now. Could i have an update on who is still alive, or standing, and such?

Geffano has been taken down, and he and peyton are on another room. All three thugs are still standing, but thug number 1 seems like he is about to go down. also, the goblin is gone. Peyton and Apa are both up.

Sirrus, feeling an encouraging surge of energy pulsate through his body, find that maybe he isn't as exhausted as he thought, and maybe he has a bit more fight in him.
He will cast witch bolt on thug number 3, nat 20 to hit for a measly 6 lightning damage.  -.-
He will use his bonus action to summon a shadow blade.

You fire off the lightning once more, the one with enough force to destroy the undead abomination, to reduce it to a mere puddle. However, the thug holds out his mace, absorbing the magical lightning. He grunts, screaming as lightning seeps through his leather handle and into his arm.

The detective walks over to the thug Sirrus was fighting, and uses the help action, giving advantage on Sirrus's next attack roll. It is now Peyton's turn once more.

Peyton rubs her chin at looks up at the window she jumped through.

With a shrug, she bends her legs and leaps up with a soft grunt on landing. Looking around she spies the remaining thug and takes a swing at him!

whack Attack: 15 Damage: 10

I do belive there are 3 remaining, by order of thug 1, thug 2, and thug 3. So which one do you attack?

The one that is most hurt.

That would be Thug number 2. Your attack manages to hit him in the head, nocking him out. Thug number 3 is left standing, and watches his friend get rag dolled. He tries spinning while holding his mace out, for 2 attacks. One at Apa, one at Peyton. Attack: 15 Damage: 5, against Apa. Attack: 10 Damage: 8 against Peyton. It is now Apa's turn.

Apa deflects the Thug's spin attack and mocks him. "You need better dance lessons. Drop your weapon or face your death"

If Thug doesn't surrender she will attack

Attack: 19 Damage: 10
If the attack hits disadvantage imposed on Thug's next attack

The thug begins weeping and drops his mace. His mumbling is unintelligible but you can hear "dance lessons" in the blathering. Thug number 3 is out for the count, as he has lost the will to fight any longer.

It is Sirrus's turn.

Sirrus sheathes his blades, (metaphorically since he wasn't using any lol) and checks to make sure if anyone on his side needs healing.  (He doesn't actually have anything to help, just surveying the battlefield.)
He'll go to the thug, untying a length of rope from around his waist and tying the fellows arms behind his back.
Slight of Hand check to tie a strong knot results are 19. (10 is needed
DC 20 athletics check to burst the rope.
"What do we do with this one?"

Apa looks at the carnage and peers out where the boss leapt from "No questioning him....Seems pretty dead. It is too bad the goblin has fled. These" She points to the thugs "Are too drunk to answer questions. Perhaps the desk has answers or maybe the detective would like to check?"

The detective points to a spot in the room. "Have you gone blind? There's still one of them left standing!" 

Thug number one, the first and final thug, stands across the room, his back turnt to you all. He looks backwards, And his eyes no longer hold that of a drunken stupor. His eyes hold something fierce. "I will not stop, until you all are dead." He says, as if stating a fact with an iron willed voice. Somehow, he is no longer drunk.

It is Peyton's turn.

Apa turns around and sees the no longer drunk thug getting ready to attack. She sighs loudly. "Well if you want to die then we will oblige"