First century Jewish women did not have the legal right to divorce their husbands, only the men had that right. In addition, women would not have custody of children unless her husband did not want custody. However, you are right that divorce would leave some women penniless unless she had family wealth. She could end up having to support herself by begging or prostitution. Marriage was strictly a business arrangement between families. I suspect Jesus' attitude toward divorce was intended to be a protective measure for women rather than an immutable demand that miserable people 2000 years later stay together. Fortunately the status of women in most nations has improved a bit since Jesus' time and most women can find a way to support herself and her children. This is often a far better choice than staying together "for the children " if that forces children to grow up in a home marked by rancor, bitterness, and emotional or physical abuse.