PP As Casablanca says you sound like you are exhausted. You certainly have a lot on your plate. Are you a teacher PP because I know how stressful that is - both my son and dil are primary school teachers and the work seems never ending. They work in different schools but in both schools there are teachers off with stress related illness.
However I think you are your own worst enemy at the moment. You are not telling the GP how bad things are, and yet talking about one of the symptoms of severe depression - suicide - ok you know you won't do it (and that's called suicide ideation) but the fact that you are having suicidal thoughts means that you are most definitely suffering from depression and anxiety. I am no medic but have had 2 major episodes of depression and hospitalised each time for 3 months. I was still at work when I had my first episode (am now retired) - I was a middle manager in social services and I know all about that thing of pretending you are ok (I used to keep crying in the loo and re-applying my make-up) I went to the GP about 4 times because I was very dizzy but I didn't tell him I was also having suicidal thoughts!
Look love, you really must stop pretending you are ok because you aren't - the trouble is depression is a deceitful illness and tells us things about ourselves that aren't true. It makes us feel that we should be able to do something to stop how we are feeling, and makes us feel guilty and ashamed. We don't feel like this if we are physically ill.
SO please please go to the GP asap and be honest - you can write down yur symptons as bullet points and give it to him/her and if you burst into tears that's ok! You will not be telling the GP anything he/she hasn't heard dozens (possibly hundreds) of times before. You will then almost definitely be prescribed ADs and in the majority of cases they are very effective. They do take around 2 -4 weeks to kick in. They act differently on different people and sometimes you have to try a couple before they are effective.
Ask the GP to sign you off sick (you are not indespensible) and you are not capable of working at this time. The longer you try, the worse it will be. You talk of feeling afraid that you will breakdown and the longer you go on as you are, the greater your chances are of getting far worse.
There is a book called "Depression the Curse of the Strong" - written by a psychiatrist (forget his name) but you can get it on Amazon.
You owe it to yourself, your little boy and your DH to get the help you need.