how to save my marriage?

Hi girls! I need some help :( 4 days ago I found out my husband had a date with a another girl he knows I know He told me I love you but I am not happy with you. Next day.. everything was weird but yesterday I found out that we are pregnant and he said he will forget about this girl with he did meet at this old job, she knows he is married but I guess she does care. I did text her and told her that I am pregnant.. well after yesterday he promised we will work in our problems and fix our marriage but today everything is bad... usually he is home at 5:30 after work.. but today he still haven't show home :( i am worried I feel like this pregnancy is going to be lonely but I try to keep my self together for my kid.. we did try for 2 years to finally get pregnant but now he is acting like this... my feelings are hurt.. this woman doesn't want to go away :( please lady's dont judge me or my married I am just looking for help