I'm so sorry you are feeling so low. Yes it does make sense & there is no need to apologise. Lass what you are feeling has nothing to do with needing to be stronger or being wrong or being selfish. Anxiety/depression etc are illnesses & like any illness they need medical treatment. As with many other conditions that can be some form of therapy or meds or both.
You mentioned that you were writing your thoughts down, that is a strategy many people find helpful. Some people keep a journal so they can look back & see any changes or patterns/triggers. Some find writing down helpful thoughts, nice things that happen, along side the negative thoughts can help.
If you find the negative thoughts running over & over again....one thing that can break the cycle is to focus on something......really really focus. You can focus on your breathing.....focus on it going in your nose....feel it filling your lungs.... feel your muscles move in response.... now feel yourself exhale...feel that pause before you take your next breath......now again giving every part of it your full attention.
There are many things you can use to focus....do some colouring in.(how hard are you pressing/how the pencil feels/what colour/getting even coverage etc) ....list how many things you can see/hear without moving your head.....stretching (start with you toes & work up stretch then release one lot of muscles at a time).... plus lots more.
I hope you manage a restful nights sleep