Honey, you're seeking therapy for YOU -- not your boyfriend. And if he's not supportive, then perhaps he's not the right one for you.

Any man that would NOT support his loved one who goes to therapy, is NOT worth the trouble. It would be like a man who would dump a woman for having cancer.

What's the difference?
You have some problems, as we all have here, and we all need help. Wouldn't HE expect YOU to support him if he had problems? Of course he would. When he gets sick, don't you have to wait on him hand and foot?
Therapy is for YOU, sweetie, not HIM. It doesn't matter what he thinks. If he's not going to be supportive, then tell him to pack his bags. You can find someone who WILL support and LOVE you UNCONDITIONALLY!!! That's the way love is supposed to be!
God bless you my friend. Please let me know what happens, will you? Big hugs, Lee