Also, despite the TV ads, I don't think FlexSeal has much chance of sealing it. Try a 2-part plastic epoxy, or plastic welding...There are kits available for this type repair, success probably depends on how much care you take in prepartion and application.
Good luck, let us know if you opt to DIY.
And, welcome to the forum.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired