I found out that my boyfriend cheated with a pregnant woman and I cannot seem to look past that?

From the beginning of our date, he told me that he cheated in his past relationship. I chose to still continue with him considering it happened before he/I started. However lately two things changed my view:
1. He is still in contact with that person that he cheated with;
2. From the limited conversation that I've seen, he cheated with her while she was pregnant and throughout the pregnancy. He said it was pure emotional and kisses/touches were involved.

I found the facts to be very disturbing and I am thinking to end it once and for all.
I do enjoy a lot his company but I am not sure I can ever look past that.

Do you have some advices to share?
I found out that my boyfriend cheated with a pregnant woman and I cannot seem to look past that?
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