What to do ?

So today is the first time I saw my dad since September.  Him and my mom are going through a divorce.  Just yesterday he texted me to try and get ahold of me and stopped by my work this morning.  He recently signed a paper for me and my sisters signing off his rights for us kids.  Now it wasn't done infront of a notary like it should have been but my mom did get it notarized. He took my car when he left along with everything that was worth something that belong to us family.  He didn't care if it was for us kids or anything.  He hasn't tried to contact us at all.  Until just yesterday.  Should I just be arms opening to him and go to his house this Sunday like he asked or just blow it off.  I love my dad and he does have his problems.  He has a messed up back so he is prescribed drugs for it.  And use to abuse it and I don't want that around me since I am ttc. I'm just torn.  He did say how he was stocking my Facebook.  And have been wanting to get ahold of me just afraid how I would react.  Don't get me wrong I came back with a big reaction and at first it did really piss me off.  And also I'm in this position where I have an amazing step father who I have called dad and love very much and has done so much more for me and my sisters and my mom then what my real dad has done.  I just need someone else's opinion on it.