Wow. There’s several things I want to get into your head, and I’m not sure I can do it just by saying them.
First, whoever this guy was, and however you feel about him, drop him. Believe me, once he’s completely out of your life, it will be an improvement. You know this. Look inside. It feels very, very scary to end a relationship, I know, especially when you’re young and haven’t been through it much, but if you look inside yourself I think you’ll find you’re more distraught at the thought of being alone than at the thought of losing this particular guy. You’re only sixteen. There WILL be others, and they will be better men.
Second, whatever pretext your parents found to fight, it was NOT your fault they split. People form relationships with each other based on each other. If they couldn’t make it work, it doesn’t mean the blame lies with you. I wish I could make the truth of that echo in your head. It’s possible that there really is no actual blame, sometimes people just can’t work out their differences as individuals. But if someone is at fault, it is certainly not a third party like yourself. Don’t resent your parents, and if one of them seems to resent you or blame you, well, try to rise above it and realize that it is their own failings they are unsatisfied with. Love them but don’t let them make you their scapegoat. And don’t you make yourself their scapegoat, either.
Third, I know this doesn’t sound helpful, but realize that moods are exagerated when you are young. The depression you’re feeling will not persist through your adult life. That may seem like good news only for the future, not now, but knowing that it won’t last might help. So know that. It gets better.
Fourth, I am so sorry to hear about your baby. That is a cause to grieve, but it is no such cause as to despair. When you are older, and have found the right guy, you can take the love you would have given this child and give a double share to her siblings. If you must punish yourself consider THAT your pennance, not suicide, in fact it is a reason to live. It is a debt you owe. And, I should add, make part of your pennance finding the patience to wait until you are at least 20 to make those siblings.
Finally, you really should give a counselor a try. You’ve got nothing to lose, even if you don’t think it would help.