Troubled Marriage

So my husband and and I met in the spring of 2017. I had recently had my son in November of 2016 and his father wanted nothing to do with him ever since finding out I was pregnant, in fact he didn't even want me to keep him. So when my husband came along he was older than I am by 10 years, had a good job and had his own house. I was in no way looking to use him but I actually found it attractive to see someone that was responsible and someone who seemed more mature, and the biggest thing was he was accepting of my having a child. So things moved pretty quickly with us, I fell for him pretty quick and he had no kids and was 32 when we met and he had always wanted kids so after a month of being together we got pregnant..I know, crazy. A couple months after finding out I was pregnant, I found out he had been texting this girl he use to talk to long distance because she lived in California and when she was moving back they were suppose to continue their relationship I guess but then he had met me. Things got rocky with us so I ended up breaking up with him and as soon as I did which he was in agreement with that it was the right thing, he goes and picks up that girl the same day and they talk for a while, sleep together..all that and I forgot to mention we had gotten engaged before this happened. After a couple of months apart, he came back and I wanted to make it work since we were having a baby. Things were good for a while and we stayed together all the way to having our daughter in March, I was so happy and enjoyed having the father around as when I had my son, I was alone and so scared being only 21 then. In May after having our daughter, things got ugly and we were not getting along. Everything felt shady and I just knew something was going on so one night when he was asleep I went through his phone and found where he was messaging girls on facebook texting them calling them gorgeous and even trying to meet up with them. this was multiple girls too, not just one. I was shattered and knew I needed to leave and so I did. He lived it up, hooked up with another girl and once he got bored of that life he came back again and I gave in. this time felt different, we deleted social media and said we would go to counseling and never did..so come November right before Thanksgiving after finding out he was back on social media behind my back and a number of other things, I left. I ended up getting my own 3 bedroom apartment, things were going okay but I was depressed and started drinking alot. He was hooking up partying and all that fun stuff. I did sleep with a couple people too that time because I just felt worthless and wanted to feel wanted by someone. Eventually you guessed it...he came back and this was right before my birthday in February and we are currently still together and pregnant. I'm 11 weeks. We are excited about the baby but lately our relationship has been rocky. this time getting back together he has actually put his hands on me and strangled me a couple of times. Even mentioned sometimes wanting to kill me and bury me in the backyard. I still stayed and my gut has been telling me something shady is happening again. I haven't caught anything so far but I'm worried and of course hes annoyed if I ask about anything. Am I wasting my time? Any suggestions on what could help my marriage? I feel hopeless and lost at times. If you've made it this far thank you for reading