Telling my friends how much i appreciate them being there for me when I’m mentally unstable

I have a lot of issues opening to people and letting them know when I’m struggling with severe anxiety and depression and don’t like leaning on people even when it helps. I have this one friend specifically who constantly reassures me she doesn’t mind me dumping things or needing to talk or distract myself and when she’s free she offers to game with me or go on drive. I want to keep telling her I really appreciate her making me feel safe and heard and comfortable to share with her but I’m scared to sound clingy or annoying