Hi Adam ~ I can certainly understand your concerns and fears. Having dealt with depression all my life, I've had to face those same things.
I think it would be a good idea to get into therapy before you have children. Therapy can help you deal with these issues and learn to cope with these fears. The therapist can give you tools to use to help you deal, plus get many unresolved issues taken care of and buried. So talk to your medical doctor and get a referral to a good therapist. You won't regret it. I've been thru therapy and it was the best gift I could have given to myself.
I wish you the very best. Please keep us posted on your progress. God bless and take care. Hugs, Lee