How do you know when it's time to end a relationship?

Well, I found out my gut instincts were right. I am 7 months pregnant and finally moved into a new home with my boyfriend of almost two years. In the very beginning, I had slept with someone else because he was going to try and work things with his ex-wife cause of the kids but was going to leave the right way for his kids sake. Then today, I had found out eight months ago ( remember I am 7 months pregnant ) that during our week break, he had been with someone else. ( I then went on two dates with his twin brother, whom I had a past with… which he did not know we had done anything that week too ) The only way I had found out was they ran into each other in person and acted so strange, and I begged it out of him. He deactivated all social media and said it was a one-time thing and that he really wants us to work because everything lately has been so much better … my walls were finally coming down. But now I feel they need to go back up again. Help?

When you have to ask, it’s time.