Hello S.,
I am so sorry that you are going through this! I know how you feel, this happened to me as well. I was 6 months pregnant when I found out and our daughter was 2-1/2. It is not easy to make decisions regarding your marriage when you're pregnant with hormones raging, and then you're raging with anger, hurt and everything else that comes into play with adultery. I know it is hard to cope with the fact that your husband could do this to you, it is painful and it feels like you do not even know who he is.
You really need to put your marriage problems aside right now and focus on the remaining time left in your pregnancy. I know that it is hard to eat and sleep, but you have to for the baby's sake. Try to stay emotionally balanced for your son's sake. My daughter saw me crying all the time and she knew the pain I was going through was from her daddy. I left him when I found out, I could not stand to look at my husband. I wanted a divorce and I wanted him to "pay" for his mistake. My daughter and I stayed at my parent's until I had the baby, and then I moved into my own place soon after.
I had to put the problems with my marriage aside so I could focus on the pregnancy, I started with complications at 32 weeks and was put on complete bedrest.
If you need time to think things through, then take time. Do not feel like you are rushed into making any decisions right now. Also do not feel like you need to do what your friends say or what your family is telling you. You need to do what is right for you and your children, what ever you choose, your husband will have to live with it. Do not let him put any blame on you, you didn't make him go and sex with someone else.
I'm sure that you have asked your husband the why's and the how's, but keep asking him questions, what went wrong with his thinking and morals that he could do this to you and your family? Why were his needs / wants more important than your family's? How many times did it happen and was it only with one person? Asking these questions, will help you sort things. Like, if he was really sorry, why did it happen more than once? Did he tell you or did you find out? My husband got / gets tired of my asking questions, but his actions and behavior lead to this, not mine.
There is so much for me to say to you because this still so fresh in my life. As for me, we are still separated, but I am trying, it is very hard and I know it will continue to be hard. Be strong and pray for strength. Try to enjoy the little bit of time left in your pregnancy.
Please feel free to write me back, my address is ____@____.com.
I know you can get through this one way or another. I wish you well and hope your baby arrives healthy.
D.