Well, after reading all this I feel so silly for just saying, no no no! But, even if he HAD made the decision to take his own life with you in mind (in addition to his own reasons) it STILL would not be your fault. He chose what he chose and I truly believe he would have done it regardless of his thoughts about your own depression!
And yes, I agree with Alffe...shame on those people for saying what they've said.
I know you're still going to question this but please...don't hold any guilt. It was his choice dear sweet lady.
Much love to you.