Sorry to hear that - you are very strong to cope with that! I was on off anti depressants in my 20s I do not reccomend - they make you numb and coming off can make you feel suicidal. The suggestions Vanessa made are great. I found 5HTP was good in combination with vitamin D and St. John’s wort. I don’t take the latter anymore but take Lions mane which is good for general brain health. Excercise really helps - your muscles are a happy factory when they are clenched they create endorphines so even a walk with some extra bum clenching! will do wonders. Reach out to others, try to have someone you check in with weekly who is a friend not a therapist. Force yourself to find joy in little things, practice gratitude - it actually really helps. Treat yourself daily - some chocolate, a face mask, whatever it is just not alcohol! Don’t be afraid to tell people you are struggling they will want to help and support you. Music is also medicine! make an upbeat playlist! You got this.
There are definitely medications that are safe to take while nursing. I hope you find a provider for medication management that can find a good fit for you. I’m so sorry you’re struggling. It’s tough taking care of kids with a broken heart.