I really struggle sometimes and I am able to offer support. In a way it is helpful to me because I feel I can still offer something to someone and it helps fight how worthless I can feel.

Helping people feels good for most people.

I never found talking to make it more of a burden on me. Helping someone move when I am in the pits of depression is an impossible task but I do like to talk and feel connected. Your friend may feel the same way.

You can always ask and try to set reasonable boundaries. I don't think your friend would want you to suffer if a little bit of their time would help you feel not so alone and help your mood.

You sound like your in a bad place and could use a friend to remind you people care about you.