Melissa,
I know this is hard. It may not feel like it now, but time heals. My father commited suicide 6 months ago. I too felt some guilt. But you MUST remember, that what ever distance that was between you and your mother, was not your fault. The distance was because of your mother's illness. You did not choose this, nor did you want things to be this way.
The most important thing now, is to know that you have so much life of your own to live. Life must continue, and you have a a new bundle of joy to love.
Stay brave, and know that you are worth loving. Things will get better.