Good lord woman - why on Earth would you have moved your son in with this man in less than 8 months ?
How could you possibly know someone well enough to do this (clearly you didn’t or you wouldn’t have been living with an abusive man) ?
How much upheaval does the poor boy need - you’ve very quickly moved some stranger into his house (or moved him from his house into a strangers) and now are pregnant (no birth control here ?). Does he factor into your thought process at all - I can’t understand why you’d think proceeding in this way was wise ?
You need to start thinking of your son first now. He is most important here. Also, you need to set an example in how to treat others and how to be treated by others.
Move out and give that poor boy some stability and love. Show him he means more to you than some new bloke.
And get yourself some standards in relation to the type of men you date - work on your self esteem, wait until you know them and the type of person they are before introducing them to your children (personally I’d be thinking a year plus for the first meeting), then gradually spend time together so you can see how they get on etc...
Have you not read the numerous threads on here from desperate women who have rushed into blending families, getting pregnant etc at breakneck speed then are stuck because the guy is not right for a variety of reasons that would have become apparent (in many cases) had they not desperately rushed into things with the first bloke that showed them some attention ? I just cannot understand why these women (including you) but a bloke above their own children.
Do what you like in terms of the pregnancy, but if you go ahead do it with the knowledge you’ll be a single parent (even if they new guy is involved). I’d question how much I’d want a baby with this guy though if he’s so abusive to your son ! What will he be like with a baby ? I’m not one to advocate cutting fathers out of babies lives (unless there are serious issues re abuse etc) so I’d personally question the wisdom of proceeding with the pregnancy but that is your choice.
To sum it up - give your head a wobble and put your child first.