Violent toddler update!

Hi, I don't know of many of you remember, but I posted in a few weeks ago world subject "violent toddler" well the very next day, I took him to the gp. Well I didn't even get half way through all my concerns when he interrupted and referred me to someone else, I'm still waiting for that appointment. Now, I've been silly enough to google the things he does, the main thing that's coming up is autism. Now by no means am I self diagnosing him, or do I think it is that, (although he has most of the signs) I honestly am clueless, I'm not a doctor I don't know, the reason I started googling is because he has changed more, his stopped talking, he used to say quite a few words, even put two word sentences together and isn't anymore, his finally clapping though! (his 18 months) now I really don't want comments saying, kids are kids etc etc they act up... I'm well aware of that, I also was very much against people diagnosing very young children with anything, until I had my own, and if you had a child who was miserable and angry 90% of the time that wouldn't even allow you to comfort them, you would probably do the same. Also, just clarifying to all those who asked and suggested it, I do smack, on the hand and on the bum, but that isn't my only form of discipline, (not like it works at all anyway!) anyway, I'm sorry for rambling, my real issue with all this is, is that my sons biological father and I are not together. My partner whom I've been with since my son was born pretty much has autism, not major, is quite mild but he has it, when my ex found this out (as I didn't particularly keep it a secret, as I didn't see an issue, his just picky about things really) he went ballistic! He told me I shouldn't have a retard around our son and alot of other things, even tried to use it in court to gain full custody of our son, along with the factmy partner has epilepsy, apparently they both cause harm to our son, (he did not gain full custody, he ended up with supervised visits and now only has him a few hours once a week) my issue now is, what if my son has autism? What sort of reaction would happen from his father? His father is what I like to call a drop kick, doesn't pay child support, abuses me constantly, showed up on my door step when his tax return went to me because he didn't pay child support demanding his money back, when I tell him our son is unwell and to give him an easy day as pain releif does cover the pain but doesn't help the sickness he ignores it and goes on with his plans as usual, but, on Facebook his dad of the year! He makes out like he would do anything for our son, when if I ask him to get him lunch when he has the visit as I ran out of bread or something he makes me give him money to get him something! Sorry I'm going off track again, his dad infuriates me. Anyway, what do I do if my son has autism? Do I tell his father? Do you think his father may respond differently? His father had some very violent traits, (all of which I can not prove) and I've seen him push his nephew who has autism around because he struggles with things, he laughs at him and calls him names, I don't know what I can do, any help would be highly appreciated, again, sorry for the length and the sidetracking!