How do you deal with the emotional rollercoaster when a breakup with someone you love is still raw?

What are the worst things you tell yourself and how do you deal with it?

The problem for me is I'm cycling between accepting there's no future to hoping for one, between telling myself I can deal with being friends and wanting to end the relationship.

Neither of those feelings feel true, but it's been weeks and my heart is still going through extremes. How do you decide what to do when you can't trust your emotions?