How do you tell someone you can't trust them?

I have exactly one friend, and she always tries telling me to open up more and not hide my feelings. However, most of the times I have tried doing this with her she ends up getting angry at me (I'll do something like ask her to offer me more compliments, and she gets angry saying she's already doing all she can and feels like she says enough nice things). So how do I explain to her I can't open up to her without losing her friendship? For the record this is nothing new, anytime I try opening up to people (even therapists) things go south for me, the only problem is I was already trying to open up with her and now I need to take some steps .