DEPORTED AND I WOULD LIKE TO COME BACK TO THE US

i was deported 8 years ago for an aggravated felony after i had lived in the US for 21 years. manslaughter 1 but in my report it shows that i tried to stop it but didn't report it. Since being in panama, i have not been in any kind of trouble, graduated from an American university here in Panama, own a business for the last 5 years and have kept a steady work employment. i have 2 American kids and my father is 88 years old. his health is deteriorating and would like to be able to see him and be with him in these few years that are left in him.

My son's mom and I have talked about getting back together and getting married. right now my mom is American and has filed an I-130 and we are at the part of filing the affidavit of support papers. what i would like to know is would getting married be a better choice? or given my circumstances i would most likely be denied? what are my chances? what are my options after that?
what are the steps that i have to complete to be able to apply to come back home?

please your help would be greatly appreciated.