Eloped

Taylor
Hello so I'm 24 and I have 3 little girls and about a year ago I met a really great guy and we have had our problems with his commitment but I have given him chance and chance so about 3-4 months ago we had another situation where a young lady accused him of getting her pregnant and her spending time with our newborn so I had her meet me at his job and she's spilling all her guts and his mother is standing there too as he walks out into this hectic situation she asked him to pick between the two of us and he chooses his family and said he never wanted to see her again so a few weeks later he tells me that, he had really messed up getting involved with her and that he wanted to marry me so I look up all the info and tell him what we need to do and so we go one late night after I got off work and did it but now I'm ready to put everything out in the open and I can't cause he hasn't said anything about wanting to do a bigger ceremony for our families or anything and now I might be pregnant with our fourth child I need serious advice ladies. 
What should I do?