Hi Mirela,
This can be a tricky one, but one that there really is only one answer to:
You and your boyfriend need to sit down with your friend (and possibly her bf) and discuss these matters.
In every household there needs to be rules - and those rules need to be followed, or it makes for an unhappy homelife.
This is your home and you are graciously letting a room to your friend - not her boyfriend.
If he is staying over more and more, then he should be told that he either pays his way, or he doesnt stay over anymore.
They both need to be told that if they use something up, be it food, toilet paper, etc, then they need to replace it.
They are not there for a free ride - this is your home, remember.
There is no need for any arguments between everyone and if this girl is a good friend, then she should realise that she is doing wrong more than right.
Just have a meeting between you all and set ground rules.
If these rules are not adheared to, then maybe it should be time for them to move on.
Give them both three months - if nothing changes, they need to vacate.
If they buck up their ideas, then great.
Either way, you will win....but you really need to have that discussion first.
It wont be easy, given that she is a friend, but she needs you more than you need her at the moment, so she needs to show a bit more respect to both you and your boyfriend.