Forcing yourself to not being sad when you are, is the worst thing you can do to yourself.
Don’t try to forget your sadness. Embrace the feeling and drown in it, till you disappear. When you do, try to find others just like you. Then, comfort them, because you have experienced their feelings too.
Repeat, until you are strong enough to endure life, even if it’s not for your sake but for others.
Live with pain, live with guilt, live with every broken part of your soul, even if it’s bitter, someday or the other you will get used to it.
Doing this will definitely not make you stronger than you actually are, but,
It will not let you become vulnerable to yourself.