Credit: Instagram

Vanderpump Rules stars Kristen Doute and Tom Sandoval have clearly had a rocky relationship over the years. And while they seemed to enjoy each other's company at one time, that is certainly not the case now, as Kristen appears to be insulting her ex on Twitter.

Kristen and Tom split up after filming ended on Season 2, and they were clearly not friendly during the reunion taping. Indeed, Kristen was quite upset when Tom held hands onstage with new girlfriend Ariana Madix, while Tom expressed his dismay over the fact that Kristen is currently dating his former pal, James Kennedy.

Now, Kristen is firing off what appears to be a dig at Tom's expense. On March 25, she tweets, "If you're happy and you know it, thank your ex." Ouch.

First of all, we're thrilled for Kristen that she is currently doing so well, as she and James are definitely an adorable couple. However, we're not sure it's necessary for her to bring up the word "ex." After all, we imagine it's in both Tom and Kristen's interest to move forward. Maybe Kristen isn't thrilled that Tom recently claimed she was lying about them having hooked up earlier this year?

Do you think Kristen crossed a line with her tweet?

Source: Kristen on Twitter