Tengis19, I'm so sorry about this! (((Hugs!)))
I know you say you're just "venting," but you also ask "is it just me." No, I don't think it's just you. I've heard similar stories and believe a lot of GPs would feel the way you do. I also have a few thoughts that might help you make sense of it all, if you're interested (if not, I understand, just skip the to the end of this post).
Unfortunately, your son's partner is not as willing to tolerate your DH's (dear husband's) "grumpy" ways as the rest of the family is. If this is part of his personality, I know it may be hard for him to control it. But I'm sure there are situations where he has done so, like maybe at work, etc. So maybe he can do so with this young woman? I'm going to agree with Red that he needs to apologize - and I'll add, try not to offend this young lady again. After all, it affects you and your son, as well as DH (sigh).
But your last paragraph may be the key to a large part of the problem. Apparently, you have been at odds with this young woman since your GS was born. DH's comment may have been a sort of "last straw" for her. Even if you have done nothing wrong, if she felt you or DH were out-of-line in any way, then that may be impacting her reactions now. It seems very unfair that she's keeping you from seeing GS, due to her anger at DH. But if some of the earlier issues involved you, then, sad to say, she may feel she's justified in keeping baby away from you, as well.
I'm not sure what you mean by "her weird ways" but again, I'm sorry that you feel you "missed out on a lot." I suspect that her idea of how much you should be involved as GPs is different than yours, and, as a GM, myself, I know that can be hard to accept. When that happens, though, I'm afraid the parents' vision always prevail cuz, hey, yunno, they're the parents and we are "just" the GPs (sigh). If DH apologizes and the relationship is resumed, you and he may have to approach this grandparenting thing with a whole new view.
"My son cannot even bring baby round himself because if he tries she barricades the door so he cannot get out. "
Uh-oh. This suggests a serious marital problem to me. Even if she thinks she's 100% right in keeping GS from you, imprisoning her husband/your son like that is not ok. Marital issues may be at the heart of this. I hate to say it but maybe it's just as well if they stay away for a while till they figure out their issues.
Hoping this all works out soon and that you get to enjoy GS once again!