Ten years is actually a long time for many people to be together in this day and age. I do not believe Sara Gilbert's past relationship will impact the success or failure of her current one. Many people have very successful second marriages because they learned most of the mistakes the first time around.
Sara Gilbert's children should not be seen as an indictment in her relationship. As a matter of fact, we should assume her partner will accept the children as their own. However, her ten year commitment in the past is proof that she is capable of maintaining a long term relationship.
Of course it is possible for Sara Gilbert's marriage with Lucinda Perry to last. It is irrelevant that she has had a previous long term partner and children. Many women are in the same position as her and have found love with a different partner (whether or not of the same sex) and that second relationship has gone on to be a success. It is up to the couple to make their relationship a success and they are perfectly capable of doing that.
Considering a normal marriage has about a 50% chance of failure and considering that once someone gets a divorce the odds of them getting another divorce are much higher, I give this marriage no chance. It might take some time but I'd be shocked if they don't get divorced in the intermediate term future.
Gay or not, this marriage won't last. It might last a while, but it won't be permanent. Celebrities are self-centered and egotistical. We think they are like us, especially stars like Gilbert who seem so down-to-earth. But she's not - her very position in life makes her incapable of being so. Additionally, our society has come to believe that long-term relationships can only exist if both people feel that same intense "falling in love" feeling the entire time. So, when that feeling goes away, the relationship ends.