Fish died, I want to divide my tank?

[wildmagic713]

My first (and only) Betta died last night :( I miss the little guy :(

But I have spring break in two weeks and I was planning on dividing up my tank. I do think he died of old age, because he was a pet store Betta, and you never know how old they are and I took good care of him.

How should I go about cleaning everything in the tank? It's a 10 gallon. I have a few silk plants in there (None of my plastic ones are in there ATM because his fins weren't looking too good (They were REALLY thin) and while they all passed the panty hose test, I didn't want to risk it), the gravel, the filter, the heater, and the thermometer.

So basically my question here is:

How should I clean everything in the tank so that it is safe to put new Bettas into it in a couple of weeks?

I'm only dividing it in half, I just feel that it looks better and is more convenient than dividing it into thirds would be.

Thanks :)