First steps in MA divorce

So a few months back out of the blue my wife of 7 years left, took our 3 year old son, our animals and most of the property.she never filed any sort of paperwork and stil hasnt till this day.over the last few months since then I have lost my job and the house is in foreclosure. She is not paying most of her part of the bills..her car, her insurance, and a personal loan in her name but on our bank. She is being difficult about when I can see my son, and made it perfectly clear shes alredy dating someone else, though i have no proof it happened before she left. What do I do? What are my rights? Do I need to file against her? Isnt she breaking the law by taking my son and not having any paperwork? I was never abusive, or a drug addict or had a drinking problem and I was always faithful and shes not claiming any different, she just wanted a life change. If I take my son for the day am I legaly obligated to return him to her?
 
 It doent seem right she can take off like this and then dictate when I can see my son and at the same time not filing paperwork. She is getting unemployment, I am not yet so she has an income I have 0. How does our property work with no paperwork? If she wont pay for her car, which is actually in both our names can I take it from her? Or at least the plates since she refuses to pay the excise taxes which again are in both our names. She also isnt paying parts of her insurance..so basically she has an income wont pay any bills and I'm trying to take care of my own and my son with no income...I cant afford a lawyer and I dont want to do anythig that will hurt me. At this point after the foreclosure of the house she says we can sign an uncontested divorce..even though I dont want it she wont go to counseling, she wont talk about it an shes already with someone else...so should I both contesting? Or is it easier on everyone for the uncontested? and what should I do before that?