Struggling

I hate to admit it, but I have been a real b°°° lately. It is something that I am extremely ashamed of. I cannot blame steroids anymore. I'm pretty sure those are well out of my system. So, I'm left questioning myself. Why am I acting this way?
The only answers I can think of so far are: fear and feeling overwhelmed. Fear of what? The unknown. And that is overwhelming. In the beginning I felt mentally and emotionally strong enough to take on anything! Now I'm a little over 2 months in and I see the cracks in my armor which worries me.
The bottom line is that I am worrying and letting things get to me too much. My God is big enough and strong enough to handle anything and everything! If He is for me, who can be against me? Who, or what, shall I fear!?
It's time I get out of this emotional/mental downward spiral and start fighting back with what I know is true:
I don't know the future- God does
I know I'm not strong enough- God is
I may feel absolutely on my own sometimes, and alone- God is right beside me.
"What ever is good, what ever is true, whatever is pleasing: meditate on these things."