I know what you mean, my little girl would be 14 now and I can still get teary thinking about her. It's a strange thing and impossible to explain to someone who hasn't been through it - how you can have such strong feelings for someone you never got to meet. I won't lie and say that the pain goes away, but it does get better - it probably took about 7 years for me to notice the pain becoming less sharp. Now it's just a part of my internal background unless I focus on it closely.
I'm sorry to hear antidepressants didn't seem to work so well for you last time, that must have been disappointing. I don't know what you tried - maybe you tried a few different types, but maybe you haven't hit on the right one for you yet? Could be worth working with your doctor to try something different this time around? I don't know, I can't talk from any experience about success with meds as I'm still waiting for mine to kick in after starting on the weekend. Right now I feel as blah as ever, I'm just working on hope that these will be the ones that do it for me.
Don't be afraid to try a different doctor too if you aren't confident with your regular GP wrt mental health. Different doctors have different strengths; I'm seeing a different GP than my usual one for my depression and am really glad I did. Doesn't mean my GP is no good - just that this is not his area of expertise.
I do think though that you should consider seeing a counsellor or therapist as well. Even if pills help you feel better, you've got a lot of stuff to deal with and I'm guessing some help with that wouldn't go astray.
It must be really hard with your wife not supporting your choice to get help last time. Maybe if you want to try again, you could do it "on the quiet" - it might be better for your own success not to have that added stress for now. If things go well you could choose when/if to share that you've been having treatment.
Not dying is certainly the best thing you can do for your family! I'm sure they love you more than you know and would be devastated if you were gone.
Putting my virtual arm around your shoulder...